As filed with the Securities and Exchange Commission on May 18, 2005

Registration No. 333-124502

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549

PRE-EFFECTIVE AMENDMENT NO. 1
FORM S-3
REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933

Southwest Bancorp, Inc.
(Exact name of registrant as specified in its charter)

Oklahoma	73-1136584
(State or other jurisdiction of incorporation or organization)	(I.R.S. Employer Identification Number)

608 South Main Street
Stillwater, Oklahoma 74074
405.372.2230
(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

Rick Green
President and Chief Executive Officer
Southwest Bancorp, Inc.
608 South Main Street
Stillwater, Oklahoma 74074
405.372.2230
(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:

James I. Lundy, III, Esquire
1700 Pennsylvania Avenue, NW
Suite 400
Washington, D.C. 20006
202.349.7130
202.318.4623 (fax) Noel M. Gruber, Esquire
Kennedy & Baris, L.L.P.
4701 Sangamore Road, Suite P-15
Bethesda, Maryland 20816
301.229.3400
301.229.2443(fax) James L. Nouss, Jr., Esquire
Harold R. Burroughs, Esquire
Bryan Cave LLP
211 North Broadway, Suite 3600
St. Louis, Missouri 63102
314.259.2000
314.552.8706 (fax)

Approximate date of commencement of proposed sale to the public: As soon as practicable after the effective date of this Registration Statement.

If any of the securities being registered on this form are to be offered pursuant to dividend or interest reinvestment plans, please check the following box.     

If the only securities being registered on this form are to be offered on a delayed or continuous basis pursuant to Rule 415 under
the Securities Act of 1933, other than securities offered in connection with dividend or interest reinvestment plans, check the
following box.     

If this form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please
check the following box and list the Securities Act registration statement number of the earlier effective registration statement for
the same offering.      ____________

If this form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.     ____________

If delivery of the prospectus is expected to be made pursuant to Rule 434, please check the following box.     

CALCULATION OF REGISTRATION FEE

Title of Each Class of Securities to be Registered	Amount to be Registered	Proposed Maximum Offering Price per Share(1)	Proposed Maximum Aggregate Offering Price(1)	Amount of Registration Fee(1)
Common stock, $1.00 par value(2)	2,415,000	$18.46	$44,580,900	$5,185.00

(1) Estimated solely for the purpose of computing the registration fee pursuant to Rule 457(c) under the Securities Act, based on the average of the high and low prices of the registrant’s common stock as reported on the Nasdaq National Market on May 16, 2005. Fee includes $4,794.00 paid with initial filing.

(2) Includes the attendant preferred stock purchase rights pursuant to the rights agreement dated as of April 22, 1999, between the registrant and Harris Trust and Savings Bank, as rights agent.

The registrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date until the registrant shall file a further amendment which specifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933 or until the registration statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a), may determine.

SUBJECT TO COMPLETION, DATED MAY 18, 2005

PROSPECTUS

2,100,000 Shares

Common Stock

We are offering 2,100,000 shares of our common stock.

Our common stock is traded on the Nasdaq National Market under the symbol “OKSB.” The last reported sale price of our common stock on the Nasdaq National Market on May 16, 2005 was $18.58 per share.

Investing in our common stock involves risks. See “Risk Factors,” beginning on page 8.

	Per Share	Total
Public offering price	$	$
Underwriting discount	$	$
Proceeds to us (before expenses)	$	$

This is a firm commitment underwriting. We have granted the underwriters a 30-day option to purchase up to an additional 315,000 shares of common stock at the same price to cover over-allotments, if any.

These securities are not deposits, savings accounts, or other obligations of any bank or savings association and are not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.

The underwriters expect to deliver the common stock to purchasers on or about      , 2005, subject to customary closing conditions.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminal offense.

Stifel, Nicolaus & Company

                 Incorporated

Edward Jones

Friedman, Billings, Ramsey & Co., Inc.

Keefe, Bruyette & Woods

SunTrust Robinson Humphrey

                , 2005

The information in this prospectus is not complete and may be changed. We may not sell these securities until the Securities and Exchange Commission declares our registration statement effective. This prospectus is not an offer to sell these securities and is not soliciting an offer to buy these securities in any state where the offer or sale is not permitted.

PROSPECTUS SUMMARY

This summary highlights information that is contained elsewhere in, or incorporated by reference into this prospectus. This summary does not contain all of the information that you should consider before investing in our common stock. You should read the entire prospectus as well as the documents incorporated by reference into this prospectus before making an investment decision. Except as otherwise indicated by the context, references in the prospectus to “we,” “our,” or “us” are to the combined business of Southwest Bancorp, Inc. From time to time we use the term “Southwest” to refer to Southwest Bancorp, Inc., the term “Stillwater National” to refer to Stillwater National Bank and Trust Company, and the term “SNB Wichita” to refer to SNB Bank of Wichita. Unless otherwise indicated, the information contained in this prospectus assumes that the underwriters will not exercise their option to purchase additional shares to cover over-allotments.

Southwest Bancorp, Inc.

Southwest Bancorp, Inc. is the financial holding company for Stillwater National Bank and Trust Company, SNB Bank of Wichita, and two consulting subsidiaries, Business Consulting Group, Inc. and Healthcare Strategic Support, Inc. We offer commercial and consumer lending, deposit, and investment services, and specialized cash management, consulting, and other financial services from twelve full-service offices in Oklahoma City, Tulsa, Chickasha, and Stillwater, Oklahoma; Dallas, Austin, and San Antonio, Texas; and Wichita, Kansas; loan production offices in Kansas City, Kansas, and on the campuses of the University of Oklahoma Health Sciences Center and Oklahoma State University-Tulsa; a marketing presence in the Student Union at Oklahoma State University-Stillwater; and on the Internet, through SNB DirectBanker^®. We were organized in 1981 as the holding company for Stillwater National, which was chartered in 1894.

Historical Growth and Performance

At March 31, 2005, we had total assets of $2.0 billion, deposits of $1.6 billion, and shareholders’ equity of $129.7 million. We became a public company in late 1993 with assets of approximately $434.0 million.

Over the five years ending on December 31, 2004, we increased our:

• Loans at an average annual rate of 14.0% per year;

• Assets at 11.5% per year;

• Net income at 16.1% per year;

• Book value per share at 13.6%; and

• Diluted earnings per share at 15.3% per year.

Our growth to date has been accomplished internally, without mergers or acquisitions, through the establishment of new offices in markets that we believed would allow us to capitalize on our strengths.

The following table highlights our recent growth and performance.

	As of and for the Three Months Ended March 31,						As of and for the Years Ended December 31,
	2005			2004			2004			2003			2002			2001			2000
	(Dollars in thousands, except per share data)
Net income	$	5,386		$	4,202		$	18,629		$	14,892		$	13,419		$	11,752		$	10,205
Diluted earnings per share		0.43			0.34			1.48			1.22			1.11			1.00			0.88
Total assets		1,994,569			1,695,241			1,913,787			1,581,564			1,351,279			1,217,796			1,204,940
Total loans (including loans held for sale)		1,673,778			1,419,282			1,623,875			1,308,836			1,101,112			931,046			912,550
Total deposits		1,628,934			1,291,626			1,500,058			1,204,125			1,021,757			904,796			945,102
Total shareholders’ equity		129,734			114,906			125,984			109,935			96,372			85,125			73,239
Book value per share		10.64			9.55			10.41			9.20			8.35			7.47			6.44
Net interest margin		4.42	%		3.96	%		4.16	%		3.80	%		3.75	%		3.53	%		3.57	%
Efficiency ratio		48.94			56.11			51.31			54.95			56.92			59.62			60.93
Return on average assets		1.08			1.02			1.03			0.99			1.05			0.96			0.87
Return on average equity		16.73			14.99			15.80			14.59			14.94			14.87			14.89

All per share information has been restated to reflect the three-for-two stock split effected in the form of a stock dividend paid August 29, 2001, and the two-for-one stock split effected in the form of a stock dividend paid August 29, 2003.

Reflects the retroactive reclassification of the allowance related to unfunded loan commitments from the allowance for loan losses to a reserve for unfunded loan commitments, which is now shown as a liability on the statement of financial condition.

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Strategic Focus

Our banking philosophy is to provide a high level of customer service, a wide range of financial services, and products responsive to customer needs. We focus on serving healthcare and health professionals, businesses and their managers and owners, and commercial and commercial real estate borrowers. Our banking philosophy has led to the development of a line of deposit, lending, and other financial products that respond to professional and commercial customer needs for speed, efficiency, and information, and complement our more traditional banking products. Our specialized financial services include integrated document imaging and cash management services designed to help our customers in the healthcare industry and other record-intensive enterprises operate more efficiently. We seek to build close relationships with businesses, professionals and their principals and to service their banking needs throughout their business development and professional lives.

We have established two management consulting subsidiaries that complement our commercial services and help to differentiate us from our competitors. Healthcare Strategic Support, Inc. provides management consulting services for physicians, hospitals, and healthcare groups. Business Consulting Group, Inc. provides marketing, strategic, logistics, and operations consulting for small and large commercial enterprises. We believe that our consulting subsidiaries help us to gain new banking customers and expand our relationship with existing customers.

Growth Strategy

We use three business models to take advantage of selected growth opportunities in markets with characteristics that we believe will allow us to capitalize on our strengths.

Niche Banking Model.     Our traditional areas of expertise focus on the special financial needs of healthcare and health professionals, businesses and their managers and owners, and commercial and commercial real estate borrowers. We developed our niche banking model in connection with our expansion into Oklahoma City in 1982 and Tulsa in 1985. Since 2002, we have used this model to expand into Dallas, Austin, and San Antonio, Texas; and Wichita and Kansas City, Kansas. At March 31, 2005, our five Texas and two Kansas offices accounted for $399.3 million in loans, excluding loan participations sold to other financial institutions.

We plan to open additional offices under our niche banking model using the following, tested approach:

• Identify markets for expansion based upon geographic concentrations of customers in our traditional areas of expertise: healthcare and health professionals, businesses and their managers and owners, and commercial and commercial real estate lending.

• Hire one or more experienced senior lenders with knowledge of the market. Specialists in cash management and other services based at other locations provide sales and support assistance. Staff is added as needed to generate and support business.

• Establish an attractive “private banking” style loan production office.

• Convert the loan production office into a full service banking office of Stillwater National or SNB Wichita after we determine that the office is likely to be successful based upon its business base, loans in process, potential deposit growth from its customers and acceptance by the community.

In our experience, it takes approximately fourteen months from establishment for a niche banking office to become profitable on a monthly basis, and twenty-seven total months to recover our initial investment.

Community Banking Model.     We began as a community bank in 1894. We continue to operate our community banking model in Stillwater, our home market, and Chickasha, Oklahoma. In those markets, we are a full-service community bank emphasizing both commercial and consumer lending. We have more than 60% of the banking deposits in the Stillwater/Payne County market. We intend to employ this community banking model to expand in favorable markets that may not meet our market criteria for our niche banking model but that we believe will support our overall growth strategy.

Secondary Market Model.     We have a long history of student and residential mortgage lending. Our secondary market activities have contributed significantly to our total loans, assets, revenues, and net income. Secondary market loan volumes and profits may vary significantly from period to period. We offer both government guaranteed and privately guaranteed student loans. During fiscal year 2004, we were one of the top 40

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student lenders in the nation by dollar volume of new guarantees originated, according to the Department of Education. We market student lending programs directly to financial aid directors at post-secondary schools. Our residential mortgage lending activities focus on one-to-four family residential borrowers in our banking markets.

We plan to continue the expansion of our secondary market activities, in particular student lending, due to the attractive nature of the business, including its government guarantees, low cost of dedicated funding, and low incremental overhead needed to maintain a larger portfolio. Our expansion in this area may slow, however, as our niche banking and community banking models continue to grow and require us to reallocate capital to those businesses.

We anticipate that part of our planned banking expansion may be accomplished through establishment of new offices as well as through acquisitions of existing banks. Our growth to date has been accomplished without banking acquisitions. We have considered acquisitions of other financial institutions and other companies, from time to time, and intend to pursue possible bank acquisitions in the future, although we do not have any specific agreements or understandings for any such acquisition at present. See “Use of Proceeds” on page 14.

Centralized Support and Control

Our support and control functions and our credit policies, including loan review, funds management, accounting, audit, compliance, and human resources, are uniform and centralized, but we have established their structure to allow prompt and flexible decision making. We offer products that are technology based, or that otherwise are more efficiently offered centrally, through our home office. These include products that are marketed through the regional offices, such as Southwest’s internet banking product for commercial and retail customers (SNB DirectBanker^®), commercial information, and item processing services (Business Mail Processing), and products marketed and managed directly by central staff, such as cash dispensing machines.

We plan to use offering proceeds to support growth.

We intend to use the net proceeds of the offering:

• To support continued expansion using our niche banking model in our current markets and in carefully selected new markets;

• To support funding and asset growth using our community banking model in favorable markets;

• To support higher levels of secondary market lending to make full use of capital while our core banking assets grow; and

• For general corporate purposes, including investment in Stillwater National or SNB Wichita.

Our principal executive offices are located at 608 South Main Street, Stillwater, Oklahoma 74074. Our telephone number is (405) 372-2230.

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THE OFFERING

Company	Southwest Bancorp, Inc.
Common stock offered by:
Southwest Bancorp, Inc. (1)	2,100,000 shares
Offering price per share	$
Shares of common stock outstanding after the offering (1)(2)	13,605,205
Net proceeds to us (1)(3)	We estimate that the net proceeds to us from the sale of 2,100,000 shares of our common stock in this offering will be approximately $36.2 million, after deducting the underwriting discount and the offering expenses payable by us.
Use of proceeds	We intend to use our net proceeds to support continued expansion in current or new markets, to support higher levels of secondary market lending, and for general corporate purposes, including investment in Stillwater National and SNB Wichita. There are no definitive plans for any acquisitions. Pending these uses, we may invest net proceeds in marketable investment securities or short-term, interest-bearing assets. See “Use of Proceeds” on page 14.
Risk factors	See “Risk Factors” beginning on page 8 and other information included or incorporated by reference in this prospectus for a discussion of factors that you should consider before investing in our common stock.
Dividends on common stock	Our quarterly dividends declared for the year ended December 31, 2004, totaled $0.28 per share. On April 1, 2005, we paid a dividend of $0.075 per share to shareholders of record on March 17, 2005. See “Price Range of Common Stock and Dividends” on page 15.
Nasdaq National Market symbol	“OKSB”

(1) Assumes that the underwriters will not exercise their option to purchase up to an additional 315,000 shares of our common stock to cover over-allotments, if any. See “Underwriting” beginning on page 25.

(2) The number of shares outstanding after the offering is based on the number of shares outstanding as of May 13, 2005, less the 689,796 shares repurchased or to be repurchased by us pursuant to a selling shareholder agreement, and plus the number of shares of common stock offered by us. If the underwriters exercise their option in full, 13,920,205 shares of our common stock will be outstanding immediately after the offering. The number of shares of our common stock outstanding after the offering shown above excludes a total of:

• 1,035,982 shares that we may issue upon the exercise of stock options outstanding as of March 31, 2005, at a weighted average exercise price of $10.93 per share; and

• 485,427 additional shares that we may issue under the Southwest Bancorp 1999 Stock Option Plan, as amended, as of March 31, 2005. See “Recent Developments” on page 5.

(3) Based upon an assumed public offering price of $18.58 per share, the last reported sale price for our common stock on the Nasdaq National Market on May 16, 2005.

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RECENT DEVELOPMENTS

Planned Redemption of Subordinated Debentures

We previously announced that we intend to redeem all of the $25.8 million of 9.30% Junior Subordinated Deferrable Interest Debentures due 2027, effective June 24, 2005. The redemption of the subordinated debentures will be concurrent with the redemption of the 9.30% Cumulative Trust Preferred Securities issued by Southwest’s subsidiary, SBI Capital Trust, which holds all of these subordinated debentures. These trust preferred securities were originally issued in June 1997, and are listed on the Nasdaq National Market under the symbol “OKSBO.” We are funding this redemption with proceeds from our issuance of trust preferred securities and subordinated debentures in October 2003. We delayed this redemption pending issuance of federal regulatory capital rules for trust preferred securities, which occurred earlier this year. We expect that the write-off of unamortized costs in connection with the redemption will reduce net income in the second quarter of 2005 by approximately $593,000. We believe that the redemption will benefit net income in future periods as the subordinated debentures are replaced with funds that bear lower interest rates. See “Capitalization” on page 16.

Purchase of Common Stock

On May 13, 2005, we entered into a Selling Shareholder Agreement with Betty B. Kerns, the Joyce P. Berry Revocable Trust, the Joe M. Berry Trust, the Berry Charitable Remainder Trust, and BKP, L.L.C. This agreement provides for the sale by these selling shareholders of a total of 689,796 shares of our common stock at a price of $18.00 per share and for the cancellation of all of the outstanding stock options previously granted to Ms. Kerns in return for a payment equal to the excess of $18.00 over the exercise price per share of options for the 10,826 shares that were exercisable by Ms. Kerns on May 13, 2005. The total consideration payable by us to the selling shareholders under the agreement is approximately $12.5 million. The shares to be repurchased under the agreement represent approximately 5.65% of the 12.2 million shares outstanding on May 13, 2005.

Approximately 680,000 of the shares subject to the agreement were held by entities related to the estate of Joyce P. Berry, who died earlier this year. The selling shareholders have indicated that a significant portion of the proceeds from their sale will be used for payment of estate related taxes. Ms. Kerns is a management official or trustee of, or has a financial interest in, each of the other selling shareholders. Ms. Kerns resigned from our board of directors on May 13, 2005.

On May 16, 2005, Southwest acquired 669,302 shares of common stock under the agreement, and all of the stock options previously granted to Ms. Kerns were cancelled. We expect to acquire the remaining 20,494 shares under the agreement on or before May 20, 2005.

Southwest, Stillwater National, and SNB Wichita will remain well-capitalized for regulatory purposes after the repurchase of shares and cancellation of options required by the agreement.

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SUMMARY CONSOLIDATED FINANCIAL DATA

The following table presents our summary consolidated financial data for each of the five years in the period ended December 31, 2004 and for the quarterly periods ending March 31, 2005 and 2004. The summary consolidated financial data should be read in conjunction with our “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and consolidated financial statements, including the accompanying notes, included in our Annual Report on Form 10-K for the year ended December 31, 2004, and our Quarterly Report on Form 10-Q for the quarter ended March 31, 2005, which are incorporated by reference in this prospectus. The financial data as of and for each of the five years ended December 31, 2000 through 2004 are derived from our audited financial statements. The financial data as of and for the quarterly periods ending March 31, 2005 and 2004 are unaudited, but include all adjustments that we believe are necessary for a fair presentation. Past performance is not necessarily predictive of future performance, and prior results should not be considered indicative of the results to be expected for any future period.

	As of and for the Three Months Ended March 31,						As of and for the Years Ended December 31,
	2005			2004			2004			2003			2002			2001			2000
	(Dollars in thousands, except per share data)
Operations Data:
Interest income	$	31,946		$	22,758		$	104,723		$	84,079		$	76,495		$	90,400		$	97,274
Interest expense		10,854			7,140			32,246			28,611			30,678			48,939			57,227
Net interest income		21,092			15,618			72,477			55,468			45,817			41,461			40,047
Provision for loan losses		4,309			1,649			12,982			8,522			5,443			4,000			3,550
Other income		3,720			3,118			14,085			14,500			12,718			10,813			8,561
Other expense		12,144			10,512			44,412			38,448			33,319			31,165			29,615
Income before taxes		8,359			6,575			29,168			22,998			19,773			17,109			15,443
Taxes on income		2,973			2,373			10,539			8,106			6,354			5,357			5,238
Net income	$	5,386		$	4,202		$	18,629		$	14,892		$	13,419		$	11,752		$	10,205
Per Share Data: (1)
Basic earnings per share	$	0.44		$	0.35		$	1.54		$	1.26		$	1.17		$	1.03		$	0.89
Diluted earnings per share		0.43			0.34			1.48			1.22			1.11			1.00			0.88
Cash dividends declared per share		0.075			0.07			0.28			0.25			0.22			0.16			0.15
Book value per share (2)		10.64			9.55			10.41			9.20			8.35			7.47			6.44
Tangible book value per share		10.62			9.53			10.39			9.18			8.33			7.45			6.42
Weighted average shares outstanding:
Basic		12,154,300			11,955,400			12,060,842			11,798,810			11,490,166			11,386,258			11,467,248
Diluted		12,628,862			12,463,367			12,548,059			12,159,620			12,052,118			11,728,844			11,585,704
Financial Condition Data: (2)
Investment securities	$	215,494		$	211,237		$	220,051		$	204,266		$	188,689		$	227,346		$	229,792
Total loans (including loans held for sale) (3)		1,673,778			1,419,282			1,623,875			1,308,836			1,101,112			931,046			912,550
Total assets (4)		1,994,569			1,695,241			1,913,787			1,581,564			1,351,279			1,217,796			1,204,940
Total deposits		1,628,934			1,291,626			1,500,058			1,204,125			1,021,757			904,796			945,102
Other borrowings		147,908			202,678			200,065			183,850			199,282			195,367			150,498
Subordinated debentures		72,180			72,180			72,180			72,180			25,787			25,787			25,787
Total shareholders’ equity		129,734			114,906			125,984			109,935			96,372			85,125			73,239
Mortgage servicing portfolio		126,202			122,751			125,353			124,366			107,733			91,120			94,545
Performance Ratios:
Return on average assets		1.08	%		1.02	%		1.03	%		0.99	%		1.05	%		0.96	%		0.87	%
Return on average equity		16.73			14.99			15.80			14.59			14.94			14.87			14.89
Net interest margin		4.42			3.96			4.16			3.80			3.75			3.53			3.57
Ratio of total dividends declared to net income		16.96			20.04			18.14			19.87			18.87			15.52			16.44
Efficiency ratio (5)		48.94			56.11			51.31			54.95			56.92			59.62			60.93
Average assets per employee (6)	$	5,502		$	4,955		$	5,098		$	4,382		$	3,938		$	3,919		$	3,783
Asset Quality Ratios:
Nonperforming assets to total loans and other real estate owned (2)(7)		1.53	%		1.25	%		1.72	%		1.34	%		1.24	%		1.06	%		1.45	%
Nonperforming loans to total loans (2)(8)		0.83			1.11			1.43			1.22			1.17			0.99			1.32
Net loan charge-offs to average total loans		0.86			0.37			0.58			0.36			0.50			0.49			0.29
Allowance for loan losses to total loans (2)(4)		1.17			1.09			1.17			1.15			1.01			1.18			1.26
Allowance for loan losses to nonperforming loans (2)(4)(8)		141.91			97.86			82.00			94.31			86.49			118.98			95.82

(continued)

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	As of and for the Three Months Ended March 31,						As of and for the Years Ended December 31,
	2005			2004			2004			2003			2002			2001			2000
Capital Ratios:
Average total shareholders’ equity to average assets		6.47	%		6.83	%		6.51	%		6.75	%		7.04	%		6.44	%		5.81	%
Tangible equity to tangible assets (2)(4)(9)		6.49			6.77			6.57			6.94			7.12			6.97			6.06
Tier 1 capital to risk-weighted assets (2)		11.03			11.10			10.88			11.13			10.38			11.15			10.36
Total capital to risk-weighted assets (2)		13.89			14.63			13.92			14.90			11.42			12.34			11.68
Leverage ratio		8.75			9.21			8.61			9.32			8.99			8.84			8.08

(1) All share and per share information has been restated to reflect the three-for-two stock split effected in the form of a stock dividend paid August 29, 2001, and the two-for-one stock split effected in the form of a stock dividend paid August 29, 2003.

(2) At period end.

(3) Net of unearned discounts but before deduction of allowance for loan losses.

(4) Reflects the retroactive reclassification of the allowance related to unfunded loan commitments from the allowance for loan losses to a reserve for unfunded loan commitments, which is now shown as a liability on the statement of financial condition.

(5) The efficiency ratio is calculated by dividing other expenses by the total of net interest income plus total other income.

(6) Average assets per employee is calculated by dividing year-to-date average assets by the number of FTE employees at period end.

(7) Nonperforming assets consist of nonperforming loans and other real estate owned.

(8) Nonperforming loans consist of nonaccrual loans, loans contractually past due 90 days or more, and loans with restructured terms.

(9) Tangible equity to tangible assets is calculated by dividing total shareholders’ equity minus goodwill by total assets minus goodwill. Mortgage loan and other loan servicing intangibles are not subtracted for purposes of this calculation.

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RISK FACTORS

Investing in our common stock involves risks. You should carefully consider the following risk factors before you decide to buy our common stock. The risk factors may cause our future earnings to be lower or our financial condition to be less favorable than we expect. In addition, other risks of which we are not aware, or which we do not believe are material, may cause earnings to be lower, or hurt our financial condition. You should also consider the other information in this prospectus, as well as in the documents incorporated by reference into this prospectus.

We may be unable to execute our growth strategy.

We have pursued, and intend to continue to pursue, an internal growth strategy, the success of which will depend primarily on generating an increasing level of loans and funding at acceptable risk and expense. There can be no assurance that we will be successful in continuing our growth strategy, however, since it depends upon economic conditions, our ability to identify appropriate markets for expansion, our ability to recruit and retain qualified personnel, our ability to fund growth at reasonable cost, sufficient capital, competitive factors, banking laws, and other factors described in this prospectus.

We intend to use the proceeds of the offering to support further growth in the level of our assets and deposits and the number of our offices, including offices in new markets that may be considerable distances from our current markets and executive headquarters. We cannot be certain as to our ability to manage increased levels of assets and liabilities, or offices in these new markets, without increased expenses and higher levels of non performing assets. We may be required to make additional investments in equipment and personnel to manage higher asset levels and loan balances, which may adversely affect earnings, shareholder returns, and our efficiency ratio. Increases in operating expenses or nonperforming assets may decrease the value of our common stock.

In addition, in the future we may acquire banks, branches of other financial institutions, or other businesses. We cannot assure you that we will be able to adequately or profitably manage any such acquisitions. The acquisition of banks, bank branches, and other businesses involves risks, including exposure to unknown or contingent liabilities, the uncertainties of asset quality assessment, the difficulty and expense of integrating the operations and personnel of the acquired companies with ours, the potential negative effects on our other operations of the diversion of management’s time and attention, and the possible loss of key employees and customers of the banks, businesses, or branches we acquire. Our failure to execute our internal growth strategy or our acquisition strategy could adversely affect our business, results of operations, financial condition and future prospects.

Changes in interest rates and other factors beyond our control may adversely affect our earnings and financial condition.

Our net income depends to a great extent upon the level of our net interest income. Changes in interest rates can increase or decrease net interest income and net income. Net interest income is the difference between the interest income we earn on loans, investments and other interest-earning assets, and the interest we pay on interest-bearing liabilities, such as deposits and borrowings. Net interest income is affected by changes in market interest rates, because different types of assets and liabilities may react differently, and at different times, to market interest rate changes. When interest-bearing liabilities mature or reprice more quickly than interest-earning assets in a period, an increase in market rates of interest could reduce net interest income. Similarly, when interest-earning assets mature or reprice more quickly than interest-bearing liabilities, falling interest rates could reduce net interest income.

Changes in market interest rates are affected by many factors beyond our control, including inflation, unemployment, money supply, international events, and events in world financial markets. We attempt to manage our risk from changes in market interest rates by adjusting the rates, maturity, repricing, and balances of the different types of interest-earning assets and interest-bearing liabilities, but interest rate risk management techniques are not exact. As a result, a rapid increase or decrease in interest rates could have an adverse effect on our net interest margin and results of operations. Changes in the market interest rates for

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types of products and services in our various markets also may vary significantly from location to location and over time based upon competition and local or regional economic factors. At March 31, 2005, our interest rate sensitivity simulation model projected that net income would decrease by 9.01% if interest rates immediately fell by 100 basis points, and would increase by 12.73% if interest rates immediately rose by 100 basis points. The model projected that net income would decrease by 5.72% if interest rates gradually fell by 100 basis points over a one-year period, and would increase by 7.79% if interest rates gradually rose by 100 basis points over a one-year period. The results of our interest rate sensitivity simulation model depend upon a number of assumptions which may not prove to be accurate. There can be no assurance that we will be able to successfully manage our interest rate risk.

Changes in local economic conditions could adversely affect our business.

Our commercial and commercial real estate lending operations are concentrated in the metropolitan areas of Stillwater, Oklahoma City, and Tulsa, Oklahoma; Dallas, Austin, and San Antonio, Texas; and Wichita and Kansas City, Kansas. Our success depends in part upon economic conditions in these markets. Adverse changes in economic conditions in these markets could reduce our growth in loans and deposits, impair our ability to collect our loans, increase our problem loans and charge-offs, and otherwise negatively affect our performance and financial condition.

Adverse changes in healthcare-related businesses could lead to slower loan growth and higher levels of problem loans and charge-offs.

We have a substantial amount of loans to individuals and businesses involved in the healthcare industry, including business and personal loans to physicians, dentists and other healthcare professionals, and loans to for-profit hospitals, nursing homes, suppliers and other healthcare-related businesses. At March 31, 2005, $370.2 million of our loans, or 29% of our portfolio loans (excluding loans held for sale), involved loans to individuals and businesses in the healthcare industry. Our strategy calls for continued growth in healthcare lending. This concentration exposes us to the risk that adverse developments in the healthcare industry could hurt our profitability and financial condition as a result of increased levels of nonperforming loans and charge-offs, and reduced loan demand and deposit growth.

Income from our secondary market activities can vary significantly from year to year. Our ability to conduct student lending activities and the profitability of our student lending operations are highly dependent on Sallie Mae and federal law.

Our secondary market activities, which consist of student lending to post-secondary students and residential mortgage lending, contribute a significant portion of our consolidated net income. The volume of residential mortgage and mortgage loans and profits depend on market interest rates, economic conditions in our markets, and competition, and can vary significantly from year to year. A significant increase in interest rates would be likely to reduce residential lending loan volume and profits.

Our student lending activities include government guaranteed loans and private student loans. Our ability to conduct our student lending operations depends significantly on the SLM Corporation, which we refer to as Sallie Mae. Sallie Mae provides substantially all of the servicing for government guaranteed and private student loans; provides liquidity through its purchases of student loans and lines of credit; and guarantees substantially all of our private student loans through its subsidiary, HEMAR Insurance Corporation of America. The majority of our private student loans have been made to students who attend schools owned by Career Education Corporation, which we refer to as CEC, through our agreements with Sallie Mae and CEC. At March 31, 2005, approximately 56% of total student loans were private CEC-related loans. The profitability of these CEC-related loans will decrease significantly, beginning in the second quarter of 2005, due to a decision by Sallie Mae to increase its servicing fees on CEC-related credits. Future changes in servicing fees or in our ability to generate private loans from CEC and other private lenders may adversely affect our net income.

The volume and profitability of our government guaranteed student loans depends upon our ability to generate loans from schools and individuals and upon federal laws and regulations that authorize government

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guaranteed student loans made by banks and other lenders and establish their terms. Although they are not possible to predict, adverse changes in these laws and regulations may reduce, or even eliminate our ability to make government guaranteed student loans, and adversely affect our net income.

Our allowance for loan losses may not be adequate to cover our actual loan losses, which could adversely affect our earnings.

We maintain an allowance for loan losses in an amount which we believe is adequate to provide for losses inherent in the portfolio. While we strive to carefully monitor credit quality and to identify loans that may become nonperforming, at any time there are loans included in the portfolio that will result in losses, but that have not been identified as nonperforming or potential problem loans. We cannot be sure that we will be able to identify deteriorating loans before they become nonperforming assets, or that we will be able to limit losses on those loans that are identified. As a result, future additions to the allowance may be necessary. Additionally, future additions may be required based on changes in the loans comprising the portfolio and changes in the financial condition of borrowers, such as may result from changes in economic conditions, or as a result of incorrect assumptions by management in determining the allowance. Additionally, federal banking regulators, as an integral part of their supervisory function, periodically review our allowance for loan losses. These regulatory agencies may require us to increase our provision for loan losses or to recognize further loan charge-offs based upon their judgments, which may be different from ours. Any increase in the allowance for loan losses could have a negative effect on our financial condition and results of operations.

Our loan portfolio contains a high percentage of commercial and commercial real estate loans in relation to our total loans and total assets. Commercial and commercial real estate loans generally are viewed as having more risk of default than residential real estate loans or other loans or investments. These types of loans also typically are larger than residential real estate loans and other consumer loans. Because the loan portfolio contains a significant number of commercial and commercial real estate loans with relatively large balances, the deterioration of one or a few of these loans may cause a significant increase in nonperforming assets. An increase in nonperforming loans could result in: a loss of earnings from these loans, an increase in the provision for loan losses, or an increase in loan charge-offs, which could have an adverse impact on our results of operations and financial condition.

Unseasoned loans may increase the risk of credit defaults in the future.

Due to our rapid growth over the past several years, a large portion of the loans in our loan portfolio and of our lending relationships are of relatively recent origin. In general, loans do not begin to show signs of credit deterioration or default until they have been outstanding for some period of time, a process referred to as “seasoning.” As a result, a portfolio of older loans may behave more predictably than a newer portfolio. Because a significant portion of our loan portfolio is relatively new, the current level of delinquencies and defaults may not be representative of the level that will prevail when the portfolio becomes more seasoned, which may be higher than current levels. If delinquencies and defaults increase, we may be required to increase our provision for loan losses, which would adversely affect our results of operations and financial condition.

We use wholesale funding sources to supplement our core deposits, which exposes us to liquidity risk and potential earnings volatility or other adverse effects if we are unable to secure adequate funding.

We rely on wholesale funding, including Federal Home Loan Bank borrowings and brokered deposits, to supplement core deposits to fund our business. At March 31, 2005, these wholesale funding sources constituted approximately 33% of our total deposits and other borrowings. Wholesale funding sources are affected by general market conditions and the condition and performance of the borrower, and the availability of funding from wholesale lenders may be dependent on the confidence these investors have in our operations. The continued availability to us of these funding sources cannot be assured, and we may find it difficult to retain or replace them at attractive rates as they mature. Our liquidity will be constrained if we are unable to renew our wholesale funding sources or if adequate financing is not available to us in the future at acceptable rates of interest or at all. We may not have sufficient liquidity to continue to fund new loans, and we may need to liquidate loans or other assets unexpectedly in order to repay obligations as they mature. If

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we do not have adequate sources of liquidity at attractive rates, we may have to restrain the growth of assets or reduce our asset size, which may adversely affect shareholder value.

We rely on our management and other key personnel, and the loss of any of them may adversely affect our operations.

We are and will continue to be dependent upon the services of our executive management team. In addition, we will continue to depend on our ability to retain and recruit key commercial loan officers. The unexpected loss of services of any key management personnel, or the inability to recruit and retain qualified personnel in the future, could have an adverse effect on our business and financial condition.

The market price for our common stock may be highly volatile.

The market price for our common stock has fluctuated, ranging between $16.50 and $27.10 per share during the 12 months ended May 16, 2005. The overall market and the price of our common stock may continue to be volatile. There may be a significant impact on the market price for our common stock due to, among other things:

• Variations in our anticipated or actual operating results or the results of our competitors;

• Changes in investors’ or analysts’ perceptions of the risks and conditions of our business;

• The size of the public float of our common stock;

• Regulatory developments;

• The announcement of acquisitions or new branch locations by us or our competitors;

• Market conditions; and

• General economic conditions.

Additionally, the average daily trading volume for our common stock as reported on the Nasdaq National Market was approximately 32,000 shares during the twelve months ended May 16, 2005, with daily volume ranging from a low of 3,000 shares to a high of approximately 193,500 shares. There can be no assurance that a more active or consistent trading market in our common stock will develop. As a result, relatively small trades could have a significant impact on the price of our common stock.

Competition may decrease our growth or profits.

We compete for loans, deposits, and investment dollars with other banks and other financial institutions and enterprises, such as securities firms, insurance companies, savings associations, credit unions, mortgage brokers, and private lenders, many of which have substantially greater resources than ours. Credit unions have federal tax exemptions, which may allow them to offer lower rates on loans and higher rates on deposits than taxpaying financial institutions such as commercial banks. In addition, non-depository institution competitors are generally not subject to the extensive regulation applicable to institutions that offer federally insured deposits. Other institutions may have other competitive advantages in particular markets or may be willing to accept lower profit margins on certain products. These differences in resources, regulation, competitive advantages, and business strategy may decrease our net interest margin, may increase our operating costs, and may make it harder for us to compete profitably.

We will have broad discretion in applying the net proceeds of this offering and the use of proceeds may not enhance the market value of our common stock.

We have significant flexibility in applying the proceeds of this offering. We are not required to allocate the proceeds to any specific investment or transaction or other use. As part of your investment decision, you will not be able to assess or direct how we apply the net proceeds. We may not be able to fully or profitably deploy the proceeds of this offering. The price of our common stock may decline if the market does not view our use of the proceeds from this offering favorably.

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Government regulation significantly affects our business.

The banking industry is heavily regulated. Banking regulations are primarily intended to protect the federal deposit insurance funds and depositors, not shareholders. Stillwater National is subject to regulation and supervision by the Office of the Comptroller of the Currency. SNB Wichita is subject to regulation and supervision by the Office of Thrift Supervision. Southwest is subject to regulation and supervision by the Board of Governors of the Federal Reserve System. The burden imposed by federal and state regulations puts banks at a competitive disadvantage compared to less regulated competitors such as finance companies, mortgage banking companies and leasing companies. Changes in the laws, regulations, and regulatory practices affecting the banking industry may increase our costs of doing business or otherwise adversely affect us and create competitive advantages for others. Regulations affecting banks and financial services companies undergo continuous change, and we cannot predict the ultimate effect of these changes, which could have a material adverse effect on our profitability or financial condition. Federal economic and monetary policy may also affect our ability to attract deposits and other funding sources, make loans and investments, and achieve satisfactory interest spreads.

Our ability to pay dividends is limited by law and contract.

Our ability to pay dividends to our shareholders largely depends on Southwest’s receipt of dividends from Stillwater National. SNB Wichita does not currently pay dividends, and is not expected to do so during the next several years. The amount of dividends that Stillwater National may pay to Southwest is limited by federal laws and regulations. We also may decide to limit the payment of dividends even when we have the legal ability to pay them in order to retain earnings for use in our business. We also are prohibited from paying dividends on our common stock if the required payments on our subordinated debentures have not been made.

Restrictions on unfriendly acquisitions could prevent a takeover.

Our certificate of incorporation and bylaws contain provisions that could discourage takeover attempts that are not approved by the board of directors. The Oklahoma General Corporation Act includes provisions that make an acquisition of Southwest more difficult. These provisions may prevent a future takeover attempt in which our shareholders otherwise might receive a substantial premium for their shares over then-current market prices.

These provisions include supermajority provisions for the approval of certain business combinations and certain provisions relating to meetings of shareholders. Our certificate of incorporation also authorizes the issuance of additional shares without shareholder approval on terms or in circumstances that could deter a future takeover attempt.

In addition, we have adopted a shareholder rights plan designed to protect our shareholders against acquisitions that our board of directors believes are unfair or otherwise not in the best interests of Southwest and its shareholders. Under the rights plan, adopted in 1999 and expiring in 2009, each holder of record of our common stock, subject to the limits of the rights plan, has received, or will receive, one right per common share. The rights generally become exercisable if an acquiring party accumulates, or announces an offer to acquire, 10% or more of our voting stock. Each right entitles the holder (other than the acquiring party) to buy, under specified circumstances, shares of our common stock or equivalent securities, or shares of the acquiror’s securities, having a value of twice the right’s exercise price. Under the rights plan, we also may exchange each right, other than rights owned by an acquiring party, for a share of our common stock or equivalent securities.

Future sales of our common stock or other securities may dilute the value of our common stock.

In many situations, our board of directors has the authority, without any vote of our shareholders, to issue shares of our authorized but unissued stock, including shares authorized and unissued under our stock option plans. In the future, we may issue additional securities, through public or private offerings, in order to raise additional capital. Any such issuance would dilute the percentage of ownership interest of existing shareholders and may dilute the per share book value of the common stock. In addition, option holders may

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exercise their options at a time when we would otherwise be able to obtain additional equity capital on more favorable terms.

The sale, or availability for sale, of a substantial number of shares of common stock in the public market as a result of or following this offering could adversely affect the price of our common stock and could impair our ability to raise additional capital through the sale of equity securities.

CAUTIONARY NOTICE REGARDING FORWARD-LOOKING STATEMENTS

We make forward-looking statements in this prospectus that are subject to risks and uncertainties. We intend these statements to be covered by the safe harbor provision for forward-looking statements contained in the Private Securities Litigation Reform Act of 1995. These statements often are identifiable by the use of the words “estimate,” “goal,” “assess,” “project,” “pro forma,” “believe,” “intend,” “plan,” “anticipate,” “expect,” “target,” “objective,” “assumption,” and similar words.

These forward-looking statements include:

• statements of our goals, intentions, and expectations;

• estimates of risks and of future costs and benefits;

• expectations regarding our future financial performance and the financial performance of our operating segments;

• assessments of loan quality, probable loan losses, and the amount and timing of loan payoffs;

• assessments of liquidity, off-balance sheet risk, and interest rate risk; and

• statements of our ability to achieve financial and other goals.

These forward-looking statements are subject to significant uncertainties because they are based upon: the amount and timing of future changes in interest rates, market behavior, and other economic conditions; future laws, regulations and accounting principles; and a variety of other matters. Because of these uncertainties, the actual future results may be materially different from the results indicated by these forward-looking statements. In addition, our past growth and performance do not necessarily indicate our future results. For other factors, risks and uncertainties that could cause our actual results to differ materially from estimates and projections contained in forward-looking statements, please read the “Risk Factors” section beginning on page 8.

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USE OF PROCEEDS

Based on an assumed public offering price of $18.58 per share, the last reported sale price of our common stock on the Nasdaq National Market on May 16, 2005, we estimate that the net proceeds from the sale by us of 2,100,000 shares of our common stock in this offering will be $36.2 million ($41.7 million if the underwriters’ over-allotment option is exercised in full), after deducting the underwriting discount and the aggregate offering expenses payable by us.

We intend to use the net proceeds of the offering:

• To support continued expansion using our niche banking model in our current markets and carefully selected new markets;

• To support funding and asset growth using our community banking model in favorable markets;

• To support higher levels of secondary market lending to make full use of capital while our core banking assets grow; and

• For general corporate purposes, including investment in Stillwater National or SNB Wichita.

We anticipate that a part of our planned banking expansion may be accomplished through acquisitions of existing banks, as well as through establishment of new offices. We do not, however, have any specific plans, arrangements, agreements or understandings with any other person for any acquisitions, or for the establishment of new branches or other offices.

Pending such uses, we may invest the net proceeds in marketable investment securities, short-term, interest-bearing assets including federal funds transactions, interest-bearing deposits in other banks and similar investments.

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PRICE RANGE OF COMMON STOCK AND DIVIDENDS

Historical Stock Prices.     Our common stock is traded on the Nasdaq National Market under the symbol “OKSB.” At May 16, 2005, there were approximately 2,500 record holders of our common stock. The following table shows the range of high and low sale prices for our common stock as reported on the Nasdaq National Market for the periods indicated and the cash dividends declared per share during those periods. All share price and dividend information has been adjusted to reflect the two-for-one stock split effected in the form of a stock dividend paid on August 29, 2003.

	High		Low		Dividends Declared
2003
First Quarter	$	13.36	$	11.07	$	0.0625
Second Quarter		13.71		11.18		0.0625
Third Quarter		17.83		13.63		0.0625
Fourth Quarter		18.91		14.37		0.0625
2004
First Quarter	$	18.94	$	16.11	$	0.07
Second Quarter		18.75		15.75		0.07
Third Quarter		22.21		17.70		0.07
Fourth Quarter		27.10		21.50		0.07
2005
First Quarter	$	25.45	$	17.11	$	0.075
Second Quarter (through May 16, 2005)		19.40		16.78		—

Dividend Policy.     Holders of our common stock are entitled to receive dividends that our board of directors may declare from time to time. Our board of directors establishes the dividend amount each quarter. In making this decision, the board considers operating results, financial condition, capital adequacy, regulatory requirements, shareholder returns, and other factors.

Our ability to pay dividends largely depends upon Southwest’s receipt of dividends from Stillwater National. SNB Wichita does not currently pay dividends, and is not expected to do so during the next several years. The amount of dividends that Stillwater National may pay to Southwest is limited by federal laws and regulations. Bank regulatory agencies also have authority to prohibit a bank or bank holding company from paying dividends if such payment is deemed to be an unsafe or unsound practice. In addition, we are prohibited from paying dividends on our common stock if the required payments on our subordinated debentures have not been made.

Regular dividends have been declared and paid every year since 1981, the year Southwest was organized. We have increased our dividends per common share each year since going public in 1993. We currently expect to continue to pay quarterly cash dividends, although there can be no assurance that we will continue to do so. See “Risk Factors,” beginning on page 8.

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CAPITALIZATION

The following table sets forth our capitalization at March 31, 2005. Our capitalization is presented on a historical basis, on an as adjusted basis giving effect to our common stock repurchase, on an as adjusted basis giving effect to our common stock repurchase and the sale of the shares offered by this prospectus, and on an as adjusted basis giving effect to our common stock repurchase, the sale of shares offered by this prospectus, and the redemption of our $25.8 million of 9.3% Junior Subordinated Deferrable Interest Debentures, assuming:

• the estimated net proceeds to us from the sale of 2,100,000 shares of common stock in this offering, based on an assumed public offering price of $18.58 per share, the last reported sale price of our common stock as reported on the Nasdaq National Market on May 16, 2005, after deducting the underwriting discounts and aggregate offering expenses payable by us, are $36.2 million; and

• the underwriters’ over-allotment option is not exercised.

The following information should be read in conjunction with our Management’s Discussion and Analysis of Financial Condition and Results of Operations, and our consolidated financial statements, including the accompanying notes, which are contained in our Annual Report on Form 10-K for the year ended December 31, 2004 and our Quarterly Report on Form 10-Q for the quarter ended March 31, 2005, each of which is incorporated by reference in this prospectus.

	Actual			As Adjusted for the Share Repurchase(1)			As Adjusted for the Share Repurchase and the Offering			As Adjusted for the Share Repurchase, the Offering, and the Redemption(2)
Long-term debt:
Subordinated debentures	$	72,180		$	72,180		$	72,180		$	46,393
Shareholders’ equity:
Serial preferred stock—
Undesignated, $1 par value; 1,000,000 shares authorized; none issued		—			—			—			—
Series B, $1 par value; 1,000,000 shares authorized; none issued		—			—			—			—
Common stock, $1 par value; 20,000,000 shares authorized; 12,243,042 shares issued and outstanding actual and as adjusted for the share repurchase; 14,343,042 shares issued and outstanding as adjusted for the share repurchase and the offering		12,243			12,243			14,343			14,343
Additional paid in capital		8,347			8,347			42,424			42,424
Retained earnings		112,377			112,316			112,316			111,723
Accumulated other comprehensive income		(2,709	)		(2,709	)		(2,709	)		(2,709	)
Treasury stock at cost, 49,915 shares actual; 739,711 shares as adjusted		(524	)		(12,940	)		(12,940	)		(12,940	)
Total shareholders’ equity		129,734			117,257			153,434			152,841
Total capitalization	$	201,914		$	189,437		$	225,614		$	199,234
Consolidated capital ratios:
Average equity to average total assets		6.47	%		5.88	%		7.55	%		7.52	%
Tangible equity to tangible assets		6.49			5.91			7.59			7.56
Leverage ratio		8.75			7.97			10.19			9.82
Tier 1 risk-based capital ratio		11.03			10.03			12.90			12.43
Total risk-based capital ratio		13.89			13.16			15.27			13.68

(1) On May 13, 2005, we entered into a Selling Shareholder Agreement with Betty B. Kerns, the Joyce P. Berry Revocable Trust, the Joe M. Berry Trust, the Berry Charitable Remainder Trust, and BKP, L.L.C. This agreement provides for the sale by these selling shareholders of a total of 689,796 shares of our common stock at a price of $18.00 per share, and for the cancellation of all of the outstanding stock options previously granted to Ms. Kerns in return for a payment equal to the excess of $18.00 over the exercise price per share of options to purchase 10,826 shares that were exercisable by Ms. Kerns on

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May 13, 2005. The total consideration payable by us to the selling shareholders under the agreement is approximately $12.5 million. See “Recent Developments” on page 5.

(2)

We previously announced that we intend to redeem all of the $25.8 million of 9.30% Junior Subordinated Deferrable Interest Debentures due 2027, effective June 24, 2005. The redemption of the subordinated debentures will be concurrent with the redemption of the 9.30% Cumulative Trust Preferred Securities issued by Southwest’s subsidiary, SBI Capital Trust, which holds all of these subordinated debentures. These trust preferred securities were originally issued in June 1997, and are listed on the Nasdaq National Market under the symbol “OKSBO.” We are funding this redemption with proceeds from our issuance of trust preferred securities and subordinated debentures in October 2003. We have invested those proceeds in marketable securities pending issuance of federal regulatory capital rules for trust preferred securities, which occurred earlier this year. We expect that the write-off of unamortized costs in connection with the redemption will reduce net income in the second quarter of 2005 by approximately $593,000. We believe that the redemption will benefit net income in future periods as the subordinated debentures are replaced with funds that bear lower interest rates.

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MANAGEMENT

The following table sets forth information regarding the executive officers of Southwest, Stillwater National, and SNB Wichita.

Name	Age	Position
Kerby E. Crowell	55	Executive Vice President, Chief Financial Officer, and Secretary of Southwest and Stillwater National; Director, Chief Financial Officer, and Secretary of SNB Wichita
L. Allen Glenn	35	Managing Director, Business Consulting Group, Inc., Vice President, Stillwater National
Steven M. Gobel	53	Executive Vice President, Stillwater National
Rick Green	57	President, Chief Executive Officer, and Director and Vice Chairman of the Boards of Southwest and Stillwater National, Director and Vice Chairman of the Board of SNB Wichita
Steven N. Hadley	47	President, SNB Bank of Wichita
Rex E. Horning	53	President, Stillwater Division of Stillwater National
Jerry L. Lanier	57	Executive Vice President and Chief Lending Officer of Stillwater National
Len McLaughlin	52	President, Dallas Division of Stillwater National
J. Randall Mills	50	President, Healthcare Strategic Support, Inc.
Steven M. Peterson	40	President, Austin Division of Stillwater National
Joseph P. Root	41	President, Central Oklahoma Division of Stillwater National
Kimberly G. Sinclair	49	Executive Vice President and Chief Administrative Officer of Stillwater National
Charles H. Westerheide	56	Executive Vice President and Treasurer of Stillwater National
David L. York	58	President, Tulsa Division of Stillwater National

The principal occupations and business experience of each executive officer of Southwest are shown below.

Kerby E. Crowell has served as Executive Vice President, Treasurer, and Chief Financial Officer of Southwest and Stillwater National since 1986, became Secretary of Southwest and Stillwater National in 2000, and was named Chief Financial Officer, Director, and Secretary of SNB Wichita in 2003. Mr. Crowell joined Stillwater National in 1969. He is a Past President and Board member of the Oklahoma City Chapter of the Financial Executives Institute and a Board member of the Independent Community Bankers of America’s, referred to as ICBA, credit card subsidiary, and MetaFund Corporation (an Oklahoma Community Development Financial Institution). He is past President and Director of the Oklahoma 4-H Foundation, Inc., Director and past President of the Payne County Affiliate of the American Diabetes Association, past President of the Stillwater Breakfast Kiwanis Club, the Bank Administration Institute’s Northern Oklahoma Chapter, and the North Central Chapter of Certified Public Accountants, a past member of the Payments and Technology Committee of the ICBA, and past Vice Chairman of the ICBA’s Bank Services Committee. He has also served on the Federal Reserve’s Industry Advisory Group on Electronic Check Presentment. Mr. Crowell is a graduate of the Leadership Stillwater Class XI.

L. Allen Glenn serves as Managing Director of the Business Consulting Group, Inc., a management consulting subsidiary of Southwest, and as a Vice President of Stillwater National. Mr. Glenn previously served as Vice President of Business Consulting Group, beginning in December 2001. From 2000 until

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joining Business Consulting Group and Stillwater National in December 2001, Mr. Glenn was President of Glenn Solutions, Inc., a management consulting firm that specialized in developing strategic and operational solutions for national retailers to improve their profitability and service levels. From 1995 to 2000, Mr. Glenn was a manager with Kurt Salmon Associates, an international management consulting firm to the retail consumer products and health care industries.

Steven M. Gobel serves as Executive Vice President, Audit Facilitator, and Associate Chief Financial Officer of Stillwater National. From 1990 until joining Stillwater National in September 2000, Mr. Gobel served as Senior Vice President-Finance and in other positions with Bank of America and predecessor institutions in Oklahoma and Kansas (previous institutions included NationsBank, Boatmen’s Bank of St. Louis, Bank IV of Wichita, Kansas, and Fourth National Bank of Tulsa). Mr. Gobel is a past member of the Board of Directors of the YMCA of Greater Tulsa and a past member and Chairman of the Board of Managers for the Downtown Branch of the YMCA of Greater Tulsa. From 1987 to 1990, Mr. Gobel served as a Vice President and Manager of Financial Reporting and Financial Planning for Sooner Federal Savings and Loan of Oklahoma. He is a Certified Public Accountant and prior to 1987 spent twelve years working for Touche Ross and Coopers & Lybrand in Tulsa, Oklahoma, New York City, and Milwaukee, Wisconsin.

Rick Green was appointed the Chief Executive Officer of Southwest effective January 1, 1999. Mr. Green joined Stillwater National in 1972, and prior to becoming Chief Executive Officer served as Chief Operating Officer, President of the Central Oklahoma division, and Executive Vice President of Stillwater National. He is a member of the Oklahoma City and Edmond Chambers of Commerce and has served as Chair/Ambassador of the Stillwater Chamber of Commerce, on the Oklahoma State University Alumni Association Homecoming and Honor Students Committees, as Chairman of Payne County Youth Services, as Co-Chairman of the United Way of Stillwater Fund Drive, and as a member of the Advisory Board of the Oklahoma State University Technical Institute. He is a member of the Commercial Real Estate Association of Oklahoma City, the Oklahoma and Oklahoma City Homebuilders Associations, and past member of the Stillwater Medical Center Committee on Physician Recruitment. Mr. Green is also a member of Leadership Stillwater and Leadership Oklahoma City. Mr. Green continues to be active as an alumnus of Oklahoma State University, serving on various committees and boards, including the Board of Governors of the Oklahoma State University Development Foundation, and is a member of the Oklahoma State University College of Business Alumni Hall of Fame.

Steven N. Hadley was named President and CEO of SNB Wichita in October 2004. Mr. Hadley has over twenty-three years of banking experience. Prior to joining SNB Wichita, Mr. Hadley spent four years with Commerce Bank in their Wichita and Garden City, Kansas markets. Before that, he was with Bank of America in Garden City, Kansas. Mr. Hadley holds a bachelors degree in Agricultural Economics from Kansas State University. He is a member of the booster club for the KAPAUN Mt. Carmel High School and is involved in the Wichita Swim Club and the St. Thomas Aquinas Catholic Church.

Rex E. Horning was appointed President of the Stillwater Division of Stillwater National in May 2001. Mr. Horning previously served as Senior Vice President of Central National Bank and Commerce Bank in Wichita, Kansas from 1998 to May 2001, and as President and Chief Executive Officer of First State Bank and Trust Company, Pittsburg, Kansas, from 1991 to 1998. Mr. Horning currently serves on the Executive Committee of the Oklahoma State University Alumni Association, is a Trustee for the Oklahoma State University Foundation, is Board Chairman of the Stillwater Chamber of Commerce, serves on the Board of Directors of the State Chamber of Commerce, and is President of Oklahoma State University’s William S. Spears’ College of Business Associates.

Jerry L. Lanier was appointed Executive Vice President and Chief Lending Officer of Stillwater National in 2001. Mr. Lanier previously served as Executive Vice President-Credit Administration beginning in December 1999, supervising this area company-wide, and from January 1998 to December 1999, served as Senior Vice President in Credit Administration. From 1992 until joining Stillwater National in 1998, Mr. Lanier was a consultant specializing in loan review. During this same period he also served as court-appointed receiver for a number of Oklahoma-based insurance companies. From 1982 to 1992, Mr. Lanier served as President of American National Bank and Trust Co. of Shawnee, Oklahoma including service as Chief Executive Officer from 1987 to 1992. From 1970 to 1981, he was a National Bank Examiner in

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Oklahoma City, Oklahoma and Dallas, Texas, and, while an examiner, served as Regional Director of Special Surveillance for the OCC from 1979 to 1981. Mr. Lanier has served as United Way Drive Chairman and President; Chairman of the Shawnee Advisory Board of Oklahoma Baptist University; Director of the Shawnee Chamber of Commerce; Director and Chairman of the Youth and Family Resource Center; and President and Trustee of the Shawnee Educational Foundation.

Len McLaughlin was appointed as President of SNB Bank of Dallas, the Texas Division of Stillwater National, in May 2002. Mr. McLaughlin previously served as President and CEO of First Independent National Bank in Plano, Texas, and as President/CEO of Preston National Bank in Dallas, Texas. From 1989 to 1998, Mr. McLaughlin was with Compass Bancshares, serving as President of a subsidiary bank, Central Bank N.A. in Anniston, Alabama; and later as Chief Retail Executive for Compass Bank in Dallas, Texas. Mr. McLaughlin began his banking career with First National Bank of Boston’s Dallas, Texas office. He has served as Chairman of the March of Dimes fund drive, United Way Fund Drive Chairman, President of the local chapter of the American Cancer Society, Director of the Little Light House, and is Honorary Co-Chairman of the Business Advisory Council of the National Republican Congressional Committee.

J. Randall Mills was appointed President of Healthcare Strategic Support, Inc. in 2003. Mr. Mills holds a Bachelor of Science degree in Accounting from Southwest Missouri State University; a Master of Health Administration from the University of Colorado; and a PhD in Sociology from Oklahoma State University. Prior to his employment with Healthcare Strategic Support, Inc., he was a healthcare consultant for Madole & Wagner, PLLC where he was responsible for marketing, administration, and client services for individual physicians, medical groups, and hospital clients on medical group practice, managed care, marketing, networking, strategic planning, and development issues. He is a fellow of the American College of Healthcare Executives, and a member of the Medical Group Management Association, American Society of Certified Public Accountants, and Oklahoma Society of Certified Public Accountants.

Steven M. Peterson was appointed President of SNB Bank of Austin in September 2004. Mr. Peterson previously served as City President for Compass Bank in Williamson County, Texas, and Commerce Bank in Wichita, Kansas from 1998 to August 2004. Mr. Peterson began his banking career with Fourth Financial Holding Company in Wichita, Kansas. Mr. Peterson currently serves as the President of the Georgetown Symphony and Director of the Chamber of Commerce. He has served as the Chairman of the 100,000 economic committee.

Joseph P. Root was appointed President of the Central Oklahoma Division of Stillwater National in 1997. Previously, Mr. Root was Senior Vice President in the Central Oklahoma division. Prior to joining Stillwater National in 1992, Mr. Root served as Credit Analyst from November 1987 to April 1989 and Private Banking Officer from May 1989 to July 1992 with Comerica Bank in Dallas, Texas. He is a member of the Advisory Board of the Greater Oklahoma City Chamber of Commerce, a member of the State Chamber of Commerce of Oklahoma, a graduate of Leadership Oklahoma City, and President of Infant Crisis Services, Inc., a local charitable organization that provides basic necessities to underprivileged children.

Kimberly G. Sinclair was appointed Chief Administrative Officer in 1995 and has been Executive Vice President of Stillwater National since 1991. Prior to 1991, she had been Senior Vice President and Chief Operations Officer of Stillwater National since 1985. Ms. Sinclair joined Stillwater National in 1975. She is a member of the Stillwater Junior Service Sustainers, and serves on the Executive Board of Directors for the Stillwater United Way, and chairs the annual Day of Caring. She is past Treasurer of the Board of Trustees of the Stillwater Public Education Foundation, and a graduate of the Leadership Stillwater Class IX. She has been an Ambassador with the Stillwater Chamber of Commerce and active with the Pioneer Booster Club and Stillwater PTA.

Charles H. Westerheide was appointed Executive Vice President and Treasurer of Stillwater National in 2000. Prior to that he served as Senior Vice President and Treasury Manager. He joined Stillwater National in 1997, coming from Bank of America (previously Bank IV and NationsBank), Wichita, Kansas, where he served as Treasury/Funding Manager. Prior to joining Bank IV, Mr. Westerheide served as Executive Vice President and Chief Financial Officer of Security Bank and Trust Co., Ponca City, Oklahoma. Mr. Westerheide has held a number of community leadership positions including Chairman of the Ponca City Chamber of

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Commerce, President of the Ponca City Foundation for Progress, Inc., and a director and officer of numerous community foundations and clubs. Mr. Westerheide is a graduate of Leadership Oklahoma, Class II.

David L. York was appointed President of the Tulsa Division in March 2004. Mr. York came to Stillwater National with over thirty years in the Tulsa banking market, most recently serving as Senior Vice President and Manager of the Professional Banking Group of The F&M Bank & Trust Company in Tulsa from 1989 to 2004. From 1983 to 1989, Mr. York served in various management and senior lending positions with Utica National Bank & Trust Company, which was acquired by F&M Bank. Mr. York began his banking career with the First National Bank and Trust Company of Tulsa in 1973 and served there until 1983 in various commercial lending and management capacities. Currently, Mr. York serves on the Board of Trustees of St. Simeon’s Episcopal Home, Inc., where he was President of the Board for four years, as well as serving as Vice President of its Foundation. Additionally, Mr. York has served on the Board of Trustees of Holland Hall School as its Treasurer. Mr. York is also an Advisory Director of the Tulsa Metro Chamber of Commerce.

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SHARE OWNERSHIP OF DIRECTORS, OFFICERS AND FIVE PERCENT BENEFICIAL OWNERS

The following table sets forth as of May 13, 2005, certain information with respect to:

• the ownership of common stock by:

• each of our directors,

• each of our executive officers who was named in the summary compensation table in our proxy statement for the annual meeting of shareholders held on April 28, 2005, and

• all directors and executive officers as a group; and

• each person known by us to be the beneficial owner of 5% or more of our outstanding common stock.

The number and percentage of shares beneficially owned after the share repurchase and the offering assumes that:

• we sell 2,100,000 shares of common stock in this offering; and

• the underwriters do not exercise their option to purchase additional shares in this offering to cover over-allotments, if any; and

• we repurchase 689,796 shares beneficially owned by Betty B. Kerns. See “Recent Developments” on page 5.

For purposes of the table below, unless otherwise noted, the number of shares of common stock outstanding and related percentages exclude:

• 1,035,982 shares that we may issue upon the exercise of stock options outstanding as of March 31, 2005, at a weighted average exercise price of $10.93 per share; and

• 485,427 additional shares at that we may issue under the Southwest Bancorp 1999 Stock Option Plan, as amended, at March 31, 2005.

Unless otherwise indicated, based on information furnished by such shareholders, we believe that each person has sole voting and investment power with respect to all shares beneficially owned by such person.

	Shares Beneficially Owned as of May 13, 2005(1)						Shares Beneficially Owned After the Share Repurchase and the Offering(1)
	Number			Percentage(2)			Number			Percentage(2)
James E. Berry II		251,996	(3)		2.06	%		251,996	(3)		1.85	%
Thomas D. Berry		62,057	(4)		*			62,057	(4)		*
Joe Berry Cannon		89,598	(5)		*			89,598	(5)		*
Rick Green		159,702	(6)		1.29			159,702	(6)		1.16
J. Berry Harrison		116,902	(7)		*			116,902	(7)		*
Erd M. Johnson		200,733	(8)		1.65			200,733	(8)		1.47
David P. Lambert		38,233	(9)		*			38,233	(9)		*
Linford R. Pitts		36,350	(10)		*			36,350	(10)		*
Robert B. Rodgers		71,922	(11)		*			71,922	(11)		*
Russell W. Teubner		52,534	(12)		*			52,534	(12)		*
Kerby E. Crowell		97,515	(13)		*			97,515	(13)		*
Jerry I. Lanier		44,134	(14)		*			44,134	(14)		*
Kimberly G. Sinclair		55,108	(15)		*			55,108	(15)		*
Joseph P. Root		17,468	(16)		*			17,468	(16)		*
All Directors and Executive Officers as a Group (23 persons)		1,418,961	(17)		11.13			1,418,961	(17)		10.02
FMR Corp		1,191,975	(18)		9.77			1,191,975	(18)		8.76
Betty B. Kerns		710,477	(19)		5.82			8,955	(19)		*
Delphi Management, Inc.		614,739	(20)		5.04			614,739	(20)		4.52

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* Less than one percent of shares outstanding.

(1) Beneficial ownership is defined by rules of the Securities and Exchange Commission, and includes shares that the person has or shares voting or investment power over and, for purposes of this chart, shares that the person has a right to acquire within 60 days from May 13, 2005. Unless otherwise indicated, ownership is direct and the named individual exercises sole voting and investment power over the shares listed as beneficially owned by such person. A decision to disclaim beneficial ownership is made by the individual, not Southwest.

(2) Calculated based upon shares reported as beneficially owned by the listed persons and shares of our common stock outstanding as of May 13, 2005. In calculating the percentage ownership of each named individual and the directors and executive officers as a group, the number of shares outstanding includes any shares that the person or the group has the right to acquire within 60 days of May 13, 2005.

(3) Excludes 28,423 shares held by his spouse and children and includes 10,826 shares that Mr. Berry has the right to acquire within 60 days of May 13, 2005, pursuant to the exercise of stock options.

(4) Excludes 4,639 shares held by the Tom D. Berry Profit Sharing Plan. Includes 10,826 shares that Mr. Berry has the right to acquire within 60 days of May 13, 2005, pursuant to the exercise of stock options.

(5) Excludes 54,810 shares beneficially owned by his spouse, as trustee. Includes 10,826 shares that Mr. Cannon has the right to acquire within 60 days of May 13, 2005, pursuant to the exercise of stock options.

(6) Excludes 7,220 shares held by his spouse and children. Includes 159,702 shares that Mr. Green has the right to acquire within 60 days of May 13, 2005, pursuant to the exercise of stock options.

(7) Includes 10,826 shares that Mr. Harrison has the right to acquire within 60 days of May 13, 2005, pursuant to the exercise of stock options.

(8) Excludes 35 shares held by his spouse. Includes 9,155 shares held by Johnson Oil Partnership of which Mr. Johnson is a general partner. Includes 7,175 shares that Mr. Johnson has the right to acquire within 60 days of May 13, 2005, pursuant to the exercise of stock options.

(9) Excludes 21,000 shares held by his spouse and 3,000 shares held by a trust of which he is co-trustee. Includes 10,826 shares that Mr. Lambert has the right to acquire within 60 days of May 13, 2005, pursuant to the exercise of stock options.

(10) Includes 10,826 shares that Mr. Pitts has the right to acquire within 60 days of May 13, 2005, pursuant to the exercise of stock options.

(11) Excludes any shares owned by his father, James W. Rodgers, Jr., and his mother, Sarah Jane Berry Rodgers. Excludes 2,276 shares held by his children. Includes 10,826 shares that Mr. Rodgers has the right to acquire with 60 days of May 13, 2005, pursuant to the exercise of stock options.

(12) Includes 10,826 shares that Mr. Teubner has the right to acquire within 60 days of May 13, 2005, pursuant to the exercise of stock options.

(13) Includes 76,341 shares that Mr. Crowell has the right to acquire within 60 days of May 13, 2005, pursuant to the exercise of stock options.

(14) Includes 43,788 shares that Mr. Lanier has the right to acquire within 60 days of May 13, 2005, pursuant to the exercise of stock options.

(15) Includes 43,184 shares that Ms. Sinclair has the right to acquire within 60 days of May 13, 2005, pursuant to the exercise of stock options.

(16) Includes 15,691 shares that Mr. Root has the right to acquire within 60 days of May 13, 2005, pursuant to the exercise of stock options.

(17) Includes shares held by certain directors and executive officers as custodians under Uniform Transfers to Minors Acts, by their spouses and children, and for the benefit of certain directors and executive officers as custodians under individual retirement accounts (“IRAs”) and living trusts. Includes 555,051 shares that executive officers and directors have the right to acquire within 60 days of May 13, 2005, pursuant to the exercise of stock options. Does not include shares beneficially owned by directors of Stillwater National Bank and Trust Company or SNB Bank of Wichita who are not also directors of Southwest.

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(18) The address of FMR Corp is 82 Devonshire Street, Boston, Massachusetts 02109.

(19) The number of shares beneficially owned as of May 13, 2005, includes 580,542 shares owned by trusts of which Ms. Kerns is a fiduciary, 100,000 shares owned by a family limited liability company, of which Ms. Kerns is a management official, 8,955 shares owned jointly with Ms. Kerns’ spouse, 900 shares of restricted stock and 10,826 additional shares that Ms. Kerns had the right to acquire within 60 days of May 13, 2005, pursuant to the exercise of stock options. Ms. Kerns resigned from our board on May 13, 2005. The address of Ms. Kerns is 4111 Deer Crossing Drive, Stillwater, Oklahoma 74074.

(20) The address of Delphi Management, Inc. is 50 Rowes Wharf, Suite 540, Boston, Massachusetts 02110.

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UNDERWRITING

Subject to the terms and conditions contained in the underwriting agreement between us and the underwriters named below, for whom Stifel, Nicolaus & Company, Incorporated is acting as representative, the underwriters have severally agreed to purchase from us and we have agreed to sell to them, an aggregate of      shares of our common stock in the numbers set forth below opposite their respective names.

Underwriters	Number of Shares
Stifel, Nicolaus & Company, Incorporated
Edward D. Jones & Co., L.L.P.
Friedman, Billings, Ramsey & Co., Inc.
Keefe, Bruyette & Woods, Inc.
SunTrust Capital Markets, Inc.
Total

Under the terms and conditions of the underwriting agreement, the underwriters are committed to accept and pay for all of the shares of our common stock in this offering, if any are taken. If an underwriter defaults, the underwriting agreement provides that the purchase commitments of a non-defaulting underwriter may be increased or, in certain cases, the underwriting agreement may be terminated. In the underwriting agreement, the obligations of the underwriters are subject to approval of certain legal matters by their counsel, including, without limitation, the authorization and the validity of the shares of our common stock, and to various other conditions contained in the underwriting agreement, such as receipt by the underwriters of officers’ certificates and legal opinions.

The underwriters propose to offer the shares of our common stock directly to the public at the public offering price set forth on the cover page of this prospectus, and to certain selected dealers (who may include the underwriters) at this price, less a concession not in excess of $               per share of our common stock. The underwriters may allow, and the selected dealers may reallow, a concession not in excess of $         per share of our common stock to certain brokers and dealers. After the shares of our common stock are released for sale to the public, the offering price and other selling terms may from time to time be changed by the underwriters.

We have granted the underwriters an option, exercisable within 30 days after the date of this prospectus, to purchase up to      additional shares of our common stock at the initial public offering price less the underwriting discounts and commissions set forth on the cover page of this prospectus. If the underwriters purchase any of the additional shares of our common stock under this option, each underwriter will be committed to purchase the additional shares of our common stock in approximately the same proportion allocated to such underwriter in the table above. The underwriters may exercise the option only for the purpose of covering over-allotments, if any, made in connection with the distribution of our shares of common stock being offered.

The following table shows the per share, total offering price of the shares offered, the total underwriting discounts and commissions that we will pay to the underwriters, and the proceeds we will receive before expenses. The amounts are shown assuming both no exercise and full exercise of the underwriters’ over-allotment option to purchase additional shares. See “Use of Proceeds” on page 14.

	Per Share	Total if the Over- Allotment Option is Not Exercised	Total if the Over- Allotment Option is Exercised in Full
Public offering price	$	$	$
Underwriting discounts and commissions
Proceeds, before expenses, to us

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We expect to incur expenses of approximately $500,000 in connection with this offering. These expenses are estimated to include legal fees of $250,000, accounting fees of $75,000, printing costs of $75,000, and miscellaneous expenses of $100,000.

The offering of the shares of our common stock is made for delivery when, as and if accepted by the underwriters and subject to prior sale and to withdrawal, cancellation or modification of the offering without notice. The underwriters reserve the right to reject any order for the purchase of the shares of our common stock.

We and our executive officers and directors have agreed, for a period of 90 days after the date of this prospectus, not to offer, sell, contract to sell, pledge or otherwise dispose of, directly or indirectly, any shares of our common stock or securities convertible into or exchangeable or exercisable for any shares of our common stock, enter into a transaction that would have the same effect, or enter into any swap, hedge or other arrangement that transfers, in whole or in part, any of the economic consequences of ownership of our common stock, whether any of these transactions is to be settled by delivery of our common stock or other securities, in cash or otherwise, or publicly disclose the intention to make any such offer, sale, pledge or disposition, or to enter into any such transaction, swap, hedge or other arrangement, without, in each case, the prior written consent of the representatives of the underwriters. Each of the persons who agreed to sell common stock to us under the selling shareholder agreement agreed to the same selling restrictions applicable to our executive officers and directors from the date of that agreement until the earlier of the termination of the agreement or 180 days after the date of the agreement, and additionally agreed to enter into an agreement with the underwriters, upon the underwriters’ request, subjecting the selling shareholders to the same selling restrictions applicable to our executive officers, and directors for a period of 90 days after the date of the prospectus. See “Recent Developments” on page 5.

We have agreed to indemnify the several underwriters against, or contribute to payments the underwriters may be required to make in respect of, several liabilities, including liabilities under the Securities Act of 1933.

The common stock is traded on the Nasdaq National Market under the symbol “OKSB.”

In connection with the offering, the underwriters may engage in transactions that are intended to stabilize, maintain or otherwise affect the price of the shares of our common stock during and after the offering.

• Stabilizing transactions permit bids to purchase shares of our common stock so long as the stabilizing bids do not exceed a specified maximum.

• Over-allotment transactions involve sales by the underwriters of shares of our common stock in excess of the number of shares the underwriters are obligated to purchase. This creates a syndicate short position which may be either a covered short position or a naked short position. In a covered short position, the number of shares over-allotted by the underwriters is not greater than the number of shares that they may purchase in the over-allotment option. In a naked short position, the number of shares involved is greater than the number of shares in the over-allotment option. The underwriters may close out any short position by either exercising their over-allotment option and/or by purchasing shares in the open market.

• Syndicate covering transactions involve purchases of common stock in the open market after the distribution has been completed in order to cover syndicate short positions. In determining the source of shares to close out the short position, the underwriters will consider, among other things, the price of shares available for purchase in the open market as compared with the price at which they may purchase shares through exercise of the over-allotment option. If the underwriters sell more shares than could be covered through exercise of the over-allotment option and, therefore, have a naked short position, the position can be closed out only by buying shares in the open market. A naked short position is more likely to be created if the underwriters are concerned that after pricing there could be downward pressure on the price of the shares in the open market that could adversely affect investors who purchase in the offering.

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• Penalty bids permit the representatives to reclaim a selling concession from a syndicate member when any shares of our common stock originally sold by that syndicate member are purchased in a stabilizing or syndicate cover transaction to cover syndicate short positions.

The effect of these transactions may be to stabilize or maintain the market price of the shares of our common stock at a level above that which might otherwise prevail in the open market. The imposition of a penalty bid may also affect the price of the shares of our common stock to the extent that it discourages resales. No representation is made as to the magnitude or effect of any such stabilization or other transactions. Such transactions may be effected on the Nasdaq National Market or otherwise and, if commenced, may be discontinued at any time.

In connection with this offering, some underwriters and any selling group members who are qualified market makers on the Nasdaq National Market may engage in passive market making transactions in our common stock on the Nasdaq National Market in accordance with Rule 103 of Regulation M under the Securities Act. Rule 103 permits passive market making during the period when Regulation M would otherwise prohibit market making activity by the participants in our common stock offering. Passive market making may occur during the business day before the pricing of our offering, before the commencement of offers or sales of our common stock. Passive market makers must comply with applicable volume and price limitations and must be identified as a passive market maker. In general, a passive market maker must display its bid at a price not in excess of the highest independent bid for the security. If all independent bids are lowered below the bid of the passive market maker, however, the bid must then be lowered when purchase limits are exceeded. Net purchases by a passive market maker on each day are limited to a specified percentage of the passive market maker’s average daily trading volume in our common stock during a specified period and must be discontinued when that limit is reached. The underwriters and other dealers are not required to engage in passive market making and may end passive market making activities at any time.

Certain of the underwriters and their affiliates have provided from time to time, and may provide in the future, investment or commercial banking services for us or our affiliates for which they have received or expect to receive customary fees and commissions.

LEGAL MATTERS

The validity of the shares of our common stock offered by this prospectus and selected other legal matters in connection with the offering will be passed upon for us by the law firms of Kennedy & Baris, L.L.P., Bethesda, Maryland and James I. Lundy, III, Attorney at Law, Washington, D.C. Certain legal matters related to this offering are being passed upon for the underwriters by the law firm of Bryan Cave LLP, St. Louis, Missouri.

EXPERTS

The consolidated financial statements of Southwest appearing in Southwest’s Annual Report (Form 10-K) for the year ended December 31, 2004 and Southwest management’s assessment of the effectiveness of internal control over financial reporting as of December 31, 2004 included therein, have been audited by Ernst & Young LLP, independent registered public accounting firm, as set forth in their reports thereon, included therein, and incorporated herein by reference. Such consolidated financial statements and management’s assessment are incorporated herein by reference in reliance upon such reports given on the authority of such firm as experts in accounting and auditing.

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WHERE YOU CAN FIND MORE INFORMATION

We file annual, quarterly and special reports, proxy statements and other information with the SEC. You may read and copy any reports, statements or other information that we file with the SEC at the SEC’s public reference room at 450 Fifth Street, N.W., Washington, D.C. 20549. Please call the SEC at 1-800-SEC-0330 for further information on the public reference room. The SEC maintains a web site on the Internet at “http://www.sec.gov” that contains reports, proxy and information statements, and other information regarding companies, including Southwest Bancorp, Inc., that file electronically with the SEC. Our SEC filings also are available on our web site at http://www.oksb.com. Information on our website is not incorporated by reference into this prospectus and you should not consider information contained in our website as part of this prospectus.

We have filed a Registration Statement on Form S-3 to register the common stock to be sold in the offering. This prospectus is a part of that Registration Statement. As allowed by SEC rules, this prospectus does not contain all the information you can find in the Registration Statement or the exhibits to the Registration Statement. SEC regulations require us to “incorporate by reference” information into this prospectus, which means that important information is disclosed by referring you to another document filed separately with the SEC. The information incorporated by reference is considered part of this prospectus. Information incorporated by reference from earlier documents is superseded by information that is included in this prospectus or is incorporated by reference from more recent documents, to the extent that they are inconsistent.

DOCUMENTS INCORPORATED BY REFERENCE

This prospectus incorporates by reference the documents listed below that we have previously filed with the SEC (file no. 000-23064).

(1) Annual Report on Form 10-K for the year ended December 31, 2004;

(2) Quarterly Report on Form 10-Q for the quarter ended March 31, 2005;

(3) Current Reports on Form 8-K filed January 10, 2005, January 26, 2005, January 27, 2005, February 28, 2005, March 23, 2005, April 21, 2005, April 28, 2005, and May 17, 2005; and

(4) The description of our common stock contained in the Form 8-A relating thereto, as amended by the information contained in Part II, Item 5 of our Form 10-Q for the period ended September 30, 1999, and the description of the preferred stock purchase rights attendant to our common stock contained in the Form 8-A relating thereto.

Also incorporated by reference are additional documents that we may file with the SEC under Section 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934 after the date of this prospectus and before the termination of the offering. These additional documents will be deemed to be incorporated by reference, and to be a part of, this prospectus from the date of their filing. These documents include proxy statements and periodic reports, such as Annual Reports on Form 10-K, Quarterly Reports on Form 10- Q, and, to the extent they are considered filed, Current Reports on Form 8-K. Information incorporated by reference from later filed documents supersedes information that is included in this prospectus or is incorporated by reference from earlier documents, to the extent that they are inconsistent.

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You can obtain any of the documents incorporated by reference from us, the SEC or the SEC’s Internet web site as described above. Documents incorporated by reference, including any exhibits specifically incorporated by reference therein, are available from us without charge. You may obtain copies of documents incorporated by reference by requesting them in writing or by telephone from:

Kerby E. Crowell
Executive Vice President,
Chief Financial Officer and Corporate Secretary
Southwest Bancorp, Inc.
608 South Main Street
Stillwater, Oklahoma 74074
Telephone (405) 372-2230

You should rely only on the information contained or incorporated by reference in this prospectus. We have not authorized anyone to provide you with information that is different from what is contained in this prospectus. This prospectus is dated      , 2005. You should not assume that the information contained in this prospectus is accurate as of any date other than that date.

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TABLE OF CONTENTS
	Page
Prospectus Summary	1
Risk Factors	8
Cautionary Notice Regarding Forward-Looking Statements	13
Use of Proceeds	14
Price Range of Common Stock and Dividends	15
Capitalization	16
Management	18
Share Ownership of Directors, Officers and Five Percent Beneficial Owners	22
Underwriting	25
Legal Matters	27
Experts	27
Where You Can Find More Information	28
Documents Incorporated by Reference	28

• You should rely only on the information contained in or incorporated by reference into this prospectus. We have not, and the underwriters have not, authorized anyone to provide you with different information. If anyone provides you with different or inconsistent information, you should not rely on it.

• You should assume that the information appearing in this prospectus is accurate only as of the date on the front cover of this prospectus.

• We are not, and the underwriters are not, making an offer of these securities in any jurisdiction where the offer or sale is not permitted. Furthermore, you should not consider this prospectus to be an offer or solicitation relating to these securities if the person making the offer or solicitation is not qualified to do so, or it is unlawful for you to receive such an offer or solicitation.

2,100,000 Shares

Common Stock

Prospectus
                          , 2005

Stifel, Nicolaus & Company
Incorporated

Edward Jones

Friedman, Billings, Ramsey & Co., Inc.

Keefe, Bruyette & Woods

SunTrust Robinson Humphrey

PART II: INFORMATION NOT REQUIRED IN PROSPECTUS

Item 14.     Other Expenses of Issuance and Distribution

The expenses payable by the Company in connection with the Offering described in this Registration Statement are as follows:

Registration Fee	$	5,185
*Blue Sky Filing Fees and Expenses (Including counsel fees)		5,000
NASD Corporate Finance Fee		5,500
*Nasdaq Listing Fees		19,000
*Legal Fees		250,000
*Printing, Engraving and Edgar		75,000
*Accounting Fees and Expenses		75,000
*Other Expenses		65,315
Total	$	500,000

* Estimated

Item 15.     Indemnification of Directors and Officers

Section 1031 of the Oklahoma General Corporation Act sets forth circumstances under which directors, officers, employees and agents may be insured or indemnified against liability which they may incur in their capacities.

Article XV of the Amended and Restated Certificate of Incorporation of the Company provides that the Company shall indemnify any individual who is or was a director, officer, employee or agent of the Company, and any individual who serves or served at the Company’s request as a director, officer, partner, trustee, employee or agent of another corporation, partnership, joint venture, trust or other enterprise, in any proceeding in which the individual is made a party as a result of his or her service in such capacity, if the individual acted in good faith and in a manner reasonably believed to be in, or not opposed to, the best interests of the Company and, with respect to any criminal proceeding, he or she had no reasonable cause to believe the conduct was unlawful, unless such indemnification would be prohibited by law. An individual will not be indemnified in connection with a proceeding by or in the right of the Company in which the individual was adjudged liable to the Company, unless the court in which the suit was brought determines the individual is fairly and reasonably entitled to indemnification in view of all of the relevant circumstances.

Item 16.     Exhibits

The exhibits filed as part of this registration statement are as follows:

Exhibit Number	Description
1	Form of Underwriting Agreement
4	Rights Agreement, dated as of April 22, 1999, between Southwest Bancorp, Inc. and Harris Trust & Savings Bank, as rights agent and Form of Certificate of Designations setting forth terms of Class B, Series 1 Preferred Stock of Southwest Bancorp, Inc. referred to in the rights agreement (incorporated by reference to Exhibits 1 and 2 to Current Report on Form 8-K dated April 22, 1999)
5	Opinion of Kennedy & Baris, L.L.P., previously filed
10	Selling Shareholder Agreement dated May 13, 2005, by and among the shareholders identified on Schedule I thereto and Southwest Bancorp, Inc. (incorporated by reference to Exhibit 10.1 to Current Report on Form 8-K dated May 17, 2005)
23(a)	Consent of Ernst & Young LLP, Independent Registered Public Accounting Firm
23(b)	Consent of Kennedy & Baris, L.L.P. (included in Exhibit 5)
23(c)	Consent of James I. Lundy, III, Attorney at Law, previously filed
24	Power of Attorney, previously filed

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Item 17.     Undertakings

The undersigned registrant hereby undertakes to deliver or cause to be delivered with the prospectus, to each person to whom the prospectus is sent or given, the latest annual report to security holders that is incorporated by reference in the prospectus and furnished pursuant to and meeting the requirements of Rule 14a-3 or Rule 14c-3 under the Exchange Act; and, where interim financial information required to be presented by Article 3 of Regulation S-X is not set forth in the prospectus, to deliver, or cause to be delivered to each person to whom the prospectus is sent or given, the latest quarterly report that is specifically incorporated by reference in the prospectus to provide such interim financial information.

The undersigned registrant hereby undertakes that, for purposes of determining any liability under the Securities Act of 1933, each filing of the registrant’s annual report pursuant to section 13(a) or section 15(d) of the Securities Exchange Act of 1934 (and, where applicable, each filing of an employee benefit plan’s annual report pursuant to section 15(d) of the Exchange Act) that is incorporated by reference in the registration statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to directors, officers and controlling persons of the registrant pursuant to the foregoing provisions, or otherwise, the registrant has been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Act, and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, officer or controlling person of the registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Act and will be governed by the final adjudication of such issue.

The undersigned registrant hereby undertakes that:

(1)      For purposes of determining any liability under the Securities Act of 1933, the information omitted from the form of prospectus filed as part of this registration statement in reliance upon Rule 430A and contained in a form of prospectus filed by the registrant pursuant to Rule 424(b)(1) or (4) or 497(h) under the Securities Act shall be deemed to be part of this registration statement as of the time it was declared effective.

(2)      For the purpose of determining any liability under the Securities Act of 1933, each post-effective amendment that contains a form of prospectus shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

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SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-3 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in Stillwater, Oklahoma, on May 18, 2005.

	SOUTHWEST BANCORP, INC.
By:	/s/ RICK GREEN Rick Green President and Chief Executive Officer

Pursuant to the requirements of the Securities Exchange Act of 1934, this registration statement has been signed below by the following persons in the capacities indicated on May 18, 2005.

Name	Capacity
/s/ Rick Green	President and Chief Executive Officer, Director, Vice Chairman of the Board of Directors (Principal Executive Officer)
Rick Green
/s/ Kerby E. Crowell	Executive Vice President, Chief Financial Officer and Secretary (Principal Accounting and Financial Officer)
Kerby E. Crowell
/s/ James E. Berry II*	Director
James E. Berry II
/s/ Thomas D. Berry*	Director
Thomas D. Berry
/s/ Joe Berry Cannon*	Director
Joe Berry Cannon
/s/ J. Berry Harrison*	Director
J. Berry Harrison
/s/ Erd M. Johnson*	Director
Erd M. Johnson
/s/ David P. Lambert*	Director
David P. Lambert

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Name	Capacity
/s/ Linford R. Pitts*	Director
Linford R. Pitts
/s/ Robert B. Rodgers*	Chairman of the Board of Directors
Robert B. Rodgers
/s/ Russell W. Teubner*	Director
Russell W. Teubner

* By: /s/ Rick Green, pursuant to power of attorney
Rick Green, Attorney in Fact

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