Exhibit 99.1

PLACER SIERRA BANCSHARES

PRESS RELEASE

FOR IMMEDIATE RELEASE

For more information contact:

AT THE COMPANY:	AT FINANCIAL RELATIONS BOARD:
Ronald W. Bachli, Chairman & CEO	Tony Rossi
David E. Hooston, Chief Financial Officer	(310) 854-8317
(916) 554-4750

PLACER SIERRA BANCSHARES REPORTS $6.6 MILLION IN NET INCOME AND A 10%

INCREASE IN EARNINGS PER SHARE FROM THE PREVIOUS QUARTER

Sacramento, California – October 18, 2005 - Placer Sierra Bancshares (NASDAQ: PLSB), a $1.9 billion commercial banking company serving the Northern, Central and Southern California markets, today announced financial results for the third quarter ended September 30, 2005.

FINANCIAL HIGHLIGHTS – THIRD QUARTER 2005 VS. SECOND QUARTER 2005

• An increase of 8.9% in quarterly GAAP net income to $6.6 million from $6.1 million

• An increase of 10.0% in fully diluted GAAP earnings per share to $0.44 from $0.40

• GAAP return on average assets of 1.42% and return on average equity of 13.13%, compared to 1.33% and 12.53%, respectively

• Return on average tangible assets of 1.59% and average tangible equity of 30.16%, compared to 1.50% and 30.13%, respectively

• Net interest margin of 5.20%, compared to 5.19%

• Cost of deposits increased to 0.93% from 0.86%

• Yield on average earning assets increased to 6.34% from 6.25%

• The efficiency ratio improved to 57.01% from 59.05%

• Average loans and leases held for investment, net of deferred fees and costs, grew by $39.4 million, or an annualized 12.0%, to $1.341 billion

• Average deposits increased by $19.6 million, or an annualized 5.0%, to $1.580 billion

EARNINGS HIGHLIGHTS

Net income for the three months ended September 30, 2005, was $6.6 million, a 71.0% increase over the $3.9 million reported for the same period of 2004. Earnings per diluted share for the three months ended September 30, 2005 was $0.44, an increase of 63.0% over $0.27 per diluted share for the same period of 2004.

For the three months ended September 30, 2005, the Company’s return on average assets and return on average equity were 1.42% and 13.13%, respectively, compared with 1.05% and 8.75%, respectively, for the third quarter of 2004.

Commenting on the third quarter, Ron Bachli, Chairman and Chief Executive Officer of Placer Sierra Bancshares, said, “We maintained the strong momentum we built in the second quarter and recorded the highest level of earnings per share in the history of the Company. During the third quarter, we continued to increase our business development activities, which resulted in $198.8 million in new loan commitments and a 60.6% year-over-year increase in referral and other loan-related fees due to an increase in commercial real estate loans referred to third

parties. This helped to offset continued high levels of prepayments in the loan portfolio. We also continue to effectively manage our growth, which is reflected in our excellent asset quality, stable net interest margin, and improving efficiency ratio. We are realizing the synergies we projected from our acquisitions of Bank of Orange County and Bank of Lodi, and as a result, we continue to generate significant year-over-year improvement in our level of profitability.”

INCOME STATEMENT

The following table presents earnings and key performance indicators on both a GAAP and operating earnings basis for the three and nine months ended September 30, 2005 and 2004:

	For the Three Months Ended September 30,						For the Nine Months Ended September 30,
	2005			2004			2005			2004
	($ in thousands, except per share data)
Net income	$	6,646		$	3,887		$	17,917		$	8,538
Acquisition related:
Merger expenses, net of tax effect		—			109			—			1,550
Investment security restructuring loss, net of tax effect		—			—			—			2,210
Operating earnings	$	6,646		$	3,996		$	17,917		$	12,298
GAAP earnings per share – basic	$	0.44		$	0.27		$	1.20		$	0.61
GAAP earnings per share – diluted	$	0.44		$	0.27		$	1.18		$	0.60
GAAP return on average assets		1.42	%		1.05	%		1.30	%		0.80	%
GAAP return on average shareholders’ equity		13.13	%		8.75	%		12.22	%		6.65	%
GAAP efficiency ratio		57.01	%		66.13	%		59.89	%		73.68	%
Net interest margin		5.20	%		4.79	%		5.20	%		4.98	%
Operating earnings per share – basic	$	0.44		$	0.28		$	1.20		$	0.88
Operating earnings per share – diluted	$	0.44		$	0.27		$	1.18		$	0.87
Operating return on average assets		1.42	%		1.08	%		1.30	%		1.16	%
Operating return on average shareholders’ equity		13.13	%		9.58	%		12.22	%		9.00	%
Operating efficiency ratio		57.01	%		65.18	%		59.89	%		64.65	%

Net interest income for the third quarter of 2005 was $21.2 million, an increase of 38.3% over net interest income of $15.4 million in the same period of 2004. The increase in net interest income reflects the acquisition of First Financial Bancorp and its subsidiary Bank of Lodi on December 10, 2004, as well as the positive effect of the asset sensitive nature of our balance sheet during a period of rising interest rates.

Net interest margin for the third quarter of 2005 was 5.20%, relatively consistent with 5.19% during the second quarter of 2005 and an increase of 41 basis points over the third quarter of 2004. During the third quarter of 2005 the yield on loans increased eight basis points to 6.77% from 6.69% during the second quarter of 2005. The cost of deposits in the third quarter of 2005 increased seven basis points to 0.93% from 0.86% in the second quarter of 2005. The increase in the yield on earning assets principally reflects the impact on loans tied to indexes associated with the prime rate, while the increase in the cost of deposits principally reflects an increased cost of certificates of deposit. Certificates of deposit continue to be the Company’s singular interest rate sensitive deposit product, with all other deposit products showing little price sensitivity.

Total non-interest income for the third quarter of 2005 totaled $4.5 million, compared with $3.2 million for the third quarter of 2004, and $4.1 million for the second quarter of 2005. The growth in non-interest income over the third quarter of 2004 was primarily attributable to a 35.2% increase in service charges and fees on deposit accounts, resulting from the Company’s acquisition of First Financial Bancorp and our revised fee structure, and a 60.6% increase in referral and other loan-related fees due to an increase in commercial real estate loans referred to third parties.

Total non-interest expense for the third quarter of 2005 was $14.7 million, compared with $12.2 million for the third quarter of 2004. During the third quarter of 2004, the Company recorded merger related expenses of $177,000 ($109,000 after tax) associated with the acquisition of Southland Capital Co. and its subsidiary Bank of Orange County. The increase is principally attributable to the Company’s acquisition of First Financial Bancorp.

The Company’s efficiency ratio for the third quarter of 2005 improved to 57.01%, compared to 66.13% in the third quarter of 2004 and 59.05% in the second quarter of 2005. Excluding the impact of the previously discussed merger expenses recorded in the third quarter of 2004, the efficiency ratio in the third quarter of 2004 would have been 65.18%.

BALANCE SHEET

As of September 30, 2005, total assets were $1.860 billion, compared to $1.862 billion at June 30, 2005. Average assets for the third quarter of 2005 were $1.863 billion, compared with $1.474 billion for the same quarter of 2004, an increase of $389.2 million, or 26.4%. The increase during the twelve months ended September 30, 2005 is principally attributable to the Company’s acquisition of First Financial Bancorp.

Total loans and leases held for investment, net of deferred fees and costs, were $1.352 billion at September 30, 2005, compared with $1.326 billion at June 30, 2005, representing annualized growth of 7.8%. Average loans and leases held for investment for the third quarter of 2005 were $1.341 billion, compared with $1.022 billion for the same quarter of 2004, an increase of $318.3 million, or 31.1%. While the Company booked $198.8 million of new commitments during the three months ended September 30, 2005, the Company also experienced loan prepayments of $80.8 million. Loan growth for the twelve months ended September 30, 2005, exclusive of the loans associated with the acquisition of First Financial Bancorp, totaled $84.6 million, or 8.0%.

Total deposits decreased by $7.4 million, or an annualized 1.9%, to $1.576 billion at September 30, 2005, from $1.583 billion at June 30, 2005. Average deposits for the third quarter of 2005 were $1.580 billion, compared with $1.231 billion for the same quarter of 2004, an increase of $349.6 million, or 28.4%, principally attributable to the Company’s acquisition of First Financial Bancorp.

Total shareholders’ equity was $204.1 million at September 30, 2005, compared with $199.6 million at June 30, 2005. Average shareholders equity for the third quarter of 2005 was $200.7 million, compared with $176.7 million for the same quarter of 2004, an increase of $24.1 million, or 13.6%.

CREDIT QUALITY

The Company’s overall credit quality remained strong during the third quarter, resulting in the determination by management that no provision for the allowance for loan and lease loss was required.

Non-performing loans to total loans and leases held for investment were 0.13% and 0.24% at September 30, 2005 and June 30, 2005, respectively.

Net charge-offs were $239,000 in the third quarter of 2005, representing an annualized rate of 0.07% of average loans and leases held for investment. Net recoveries of $36,000 as a percentage of average loans and leases held for investment on an annualized basis were 0.00% for the first nine months of 2005, compared with net charge-offs of 0.15% for the nine months ended September 30, 2004. The allowance for loan and lease losses totaled $16.2 million at September 30, 2005 and represented 1.20% of loans and leases held for investment, net of deferred fees and costs, and 948.36% of non-performing loans and leases as of that date.

REGULATORY CAPITAL

Placer Sierra Bancshares’ regulatory capital ratios at September 30, 2005 are as follows:

Leverage Ratio
Placer Sierra Bancshares	8.5	%
Minimum regulatory requirement	4.0	%
Tier 1 Risk-Based Capital Ratio
Placer Sierra Bancshares	10.1	%
Minimum regulatory requirement	4.0	%
Total Risk-Based Capital Ratio
Placer Sierra Bancshares	11.2	%
Minimum regulatory requirement	8.0	%

OUTLOOK

For the fourth quarter of 2005, the Company expects fully diluted earnings per share to range from $0.45 to $0.47.

Commenting on the outlook for Placer Sierra Bancshares, Mr. Bachli said, “Economic conditions throughout our California markets are vibrant, and we are seeing a wealth of quality, low-risk lending opportunities in the commercial and commercial real estate segments. Although we expect that rising deposit costs and continued high loan prepayments will present challenges, our growth in earning assets and loan referral fees will allow us to drive further improvement in our bottom-line results. We also continue to move forward on our expansion efforts. We have three de novo branch openings scheduled for 2006, including our first full-service branch in Fresno, and three planned branch relocations that will position us in areas of Sacramento that are experiencing higher growth rates. Combined with the continued exploration of attractive acquisition opportunities, we believe our de novo strategy will help us further capitalize on some of California’s fastest growing markets.”

ABOUT PLACER SIERRA BANCSHARES

Placer Sierra Bancshares is a Northern California-based bank holding company for Placer Sierra Bank with 31 branches in an eight-county area of Northern California, including Placer, Sacramento, El Dorado, Sierra, Nevada, Amador, San Joaquin and Calaveras counties and nine branches in Southern California’s Orange and Los Angeles counties. Placer Sierra Bank and its divisions, Sacramento Commercial Bank, Bank of Orange County and Bank of Lodi, offer customers the resources of a large financial institution and the resourcefulness and superior customer service of a community bank.

Placer Sierra Bank offers a broad array of deposit products and services for both commercial and retail customers. These products include electronic banking, cash management services, electronic bill payment and investment services with an emphasis on relationship banking. Placer Sierra Bank also provides competitive loan products such as commercial loans and lines of credit, commercial real estate loans, Small Business Administration loans, residential mortgage loans, home equity lines of credit and construction loans. For more information, please visit www.placersierrabank.com.

Placer Sierra Bancshares is publicly traded on NASDAQ under the stock symbol PLSB. For more information about Placer Sierra Bancshares, please visit www.placersierrabancshares.com.

FORWARD-LOOKING STATEMENTS

This press release contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, that involve inherent risks and uncertainties. Placer Sierra Bancshares cautions readers that a number of important factors could cause actual results to differ materially from those in such forward-looking statements. All statements other than statements of historical fact are forward-looking statements. Risks and uncertainties include, but are not limited to: the possibility that personnel changes will not proceed as planned; planned acquisitions and relative cost savings cannot be realized or realized within the expected time frame; revenues are lower than expected; competitive pressure among depository institutions increases significantly; the integration of acquired businesses costs more, takes longer or is less successful than expected; the cost of additional capital is more than expected; changes in the interest rate environment reduces interest margins; general economic conditions, either nationally or in the market areas in which Placer Sierra does business, are less favorable than expected; legislation or regulatory requirements or changes adversely affect Placer Sierra’s business; changes that may occur in the securities markets; and other risks that are described in Placer Sierra’s Securities and Exchange Commission filings. If any of these uncertainties materializes or any of these assumptions proves incorrect, Placer Sierra’s results could differ materially from Placer Sierra’s expectations as set forth in these statements. Placer Sierra assumes no obligation to update such forward-looking statements.

UNAUDITED CONSOLIDATED BALANCE SHEETS

($ in thousands, except share and per share data)

	September 30, 2005			December 31, 2004
Assets:
Cash and due from banks	$	57,973		$	39,255
Federal funds sold		18,342			361
Cash and cash equivalents		76,315			39,616
Interest bearing deposits with other banks		125			125
Investment securities available-for-sale		229,719			249,916
Federal Reserve Bank and Federal Home Loan Bank stock		14,297			10,430
Loans and leases held for investment, net of allowance for loan and lease losses of $16,236 in 2005 and $16,200 in 2004		1,335,615			1,278,064
Premises and equipment, net		27,557			27,645
Cash surrender value of life insurance		43,910			42,390
Other real estate		—			657
Goodwill		101,092			101,329
Other intangible assets		12,225			14,172
Other assets		19,095			14,641
Total assets	$	1,859,950		$	1,778,985
Liabilities and shareholders’ equity:
Liabilities:
Non-interest bearing deposits	$	496,787		$	485,193
Interest bearing deposits		1,078,960			1,014,866
Total deposits		1,575,747			1,500,059
Short-term borrowings		10,674			16,265
Accrued interest payable and other liabilities		15,769			17,409
Junior subordinated deferrable interest debentures		53,611			53,611
Total liabilities		1,655,801			1,587,344
Shareholders’ equity:
Common stock		159,728			157,834
Retained earnings		45,867			33,323
Accumulated other comprehensive (loss) income		(1,446	)		484
Total shareholders’ equity		204,149			191,641
Total liabilities and shareholders’ equity	$	1,859,950		$	1,778,985
Shares outstanding		14,992,754			14,877,056
Book value per share	$	13.62		$	12.88

UNAUDITED CONSOLIDATED STATEMENTS OF INCOME

($ in thousands, except per share data)

	Three Months Ended September 30,					Nine Months Ended September 30,
	2005			2004		2005			2004
Interest income:
Interest and fees on loans and leases held for investment	$	22,864		$	15,780	$	65,348		$	45,779
Interest on loans held for sale		—			6		—			9
Interest on deposits with other banks		—			1		2			1
Interest and dividends on investment securities:
Taxable		2,540			1,496		7,493			5,498
Tax-exempt		185			130		535			394
Interest on federal funds sold		264			388		618			586
Total interest income		25,853			17,801		73,996			52,267
Interest expense:
Interest on deposits		3,696			1,930		9,793			5,069
Interest on short-term borrowings		21			25		81			142
Interest on junior subordinated deferrable interest debentures		898			490		2,494			1,382
Total interest expense		4,615			2,445		12,368			6,593
Net interest income		21,238			15,356		61,628			45,674
Provision for the allowance for loan and lease losses		—			—		—			560
Net interest income after provision for the allowance for loan and lease losses		21,238			15,356		61,628			45,114
Non-interest income:
Service charges and fees on deposit accounts		2,070			1,531		5,801			4,710
Referral and other loan-related fees		1,298			808		2,834			2,132
Loan servicing income		102			71		340			242
Gain on sale of loans, net		—			3		—			179
Revenues from sales of non-deposit investment products		204			125		570			497
(Loss) gain on sale of investment securities available-for-sale, net		(1	)		1		(56	)		(3,335	)
Increase in cash surrender value of life insurance		396			291		1,240			918
Other		402			334		1,309			1,999
Total non-interest income		4,471			3,164		12,038			7,342
Non-interest expense:
Salaries and employee benefits		7,471			6,125		22,469			18,789
Occupancy and equipment		2,039			1,747		6,030			5,169
Merger		—			177		—			2,319
Other		5,147			4,199		15,616			12,784
Total non-interest expense		14,657			12,248		44,115			39,061
Income before income taxes		11,052			6,272		29,551			13,395
Provision for income taxes		4,406			2,385		11,634			4,857
Net income	$	6,646		$	3,887	$	17,917			8,538
Earnings per share:
Basic	$	0.44		$	0.27	$	1.20		$	0.61
Diluted	$	0.44		$	0.27	$	1.18		$	0.60

UNAUDITED CONSOLIDATED AVERAGE BALANCE SHEETS

($ in thousands)

	Three Months Ended September 30,						Nine Months Ended September 30,
	2005			2004			2005			2004
Average assets:
Loans and leases, held for investment	$	1,340,592		$	1,022,290		$	1,311,779		$	991,294
Loans and leases held for sale		—			536			—			267
Investment securities available-for-sale		232,046			125,257			232,673			153,827
Federal funds sold		31,806			118,066			28,431			70,052
Interest bearing deposits with other banks		125			125			125			42
Other earning assets		14,250			9,317			12,723			8,633
Average earning assets		1,618,819			1,275,591			1,585,731			1,224,115
Other assets		244,023			198,072			252,730			194,752
Average total assets	$	1,862,842		$	1,473,663		$	1,838,461		$	1,418,867
Average liabilities and shareholders’ equity:
Average liabilities:
Non-interest bearing deposits	$	502,631		$	423,639		$	494,363		$	395,235
Interest bearing deposits		1,077,572			806,998			1,061,273			777,459
Average deposits		1,580,203			1,230,637			1,555,636			1,172,694
Other interest bearing liabilities		64,641			52,842			66,916			59,926
Other liabilities		17,252			13,503			19,901			14,766
Average liabilities		1,662,096			1,296,982			1,642,453			1,247,386
Average equity		200,746			176,681			196,008			171,481
Average liabilities and shareholders’ equity	$	1,862,842		$	1,473,663		$	1,838,461		$	1,418,867
YIELD ANALYSIS:
Average loans and leases held for investment	$	1,340,592		$	1,022,290		$	1,311,779		$	991,294
Yield		6.77	%		6.14	%		6.66	%		6.17	%
Average earnings assets	$	1,618,819		$	1,275,591		$	1,585,731		$	1,224,115
Yield		6.34	%		5.55	%		6.24	%		5.70	%
Average interest bearing deposits	$	1,077,572		$	806,998		$	1,061,273		$	777,459
Cost		1.36	%		0.95	%		1.23	%		0.87	%
Average deposits	$	1,580,203		$	1,230,637		$	1,555,636		$	1,172,694
Cost		0.93	%		0.62	%		0.84	%		0.58	%
Average interest bearing liabilities	$	1,142,213		$	859,840		$	1,128,189		$	837,385
Cost		1.60	%		1.13	%		1.47	%		1.05	%
Interest spread		4.74	%		4.42	%		4.77	%		4.65	%
Net interest margin		5.20	%		4.79	%		5.20	%		4.98	%

CREDIT QUALITY MEASURES

	At or for the Nine Months Ended 9/30/05		At or for the Six Months Ended 6/30/05		At or for the Three Months Ended 3/31/05		At or for the Year Ended 12/31/04		At or for the Nine Months Ended 9/30/04
Non-performing loans and leases to total loans and leases held for investment	0.13	%	0.24	%	0.24	%	0.22	%	0.21	%
Non-performing assets to total assets	0.09	%	0.17	%	0.20	%	0.20	%	0.19	%
Allowance for loan and lease losses to total loans and leases held for investment	1.20	%	1.24	%	1.29	%	1.25	%	1.21	%
Allowance for loan and lease losses to non-performing loans and leases	948.36	%	527.20	%	549.51	%	558.81	%	580.35	%
Allowance for loan and lease losses to non-performing assets	948.36	%	527.20	%	452.01	%	455.57	%	446.85	%
Net (charge-offs)/recoveries to average loans and leases held for investment	0.00	%	0.04	%	0.17	%	(0.15	)%	(0.15	)%

LOANS

($ in thousands)

	Balance at 09/30/05			Balance at 06/30/05			Balance at 03/31/05			Balance at 12/31/04			Balance at 09/30/04
Loans and leases held for investment:
Real estate - mortgage	$	966,523		$	949,131		$	901,956		$	892,136		$	735,971
Real estate - construction		197,975			183,886			191,834			184,317			153,552
Commercial		153,172			155,938			155,478			167,035			127,342
Agricultural		8,363			7,652			14,539			17,423			391
Consumer		10,910			10,950			9,961			11,110			10,688
Leases receivable and other		17,475			20,477			22,784			24,575			24,523
Total gross loans and leases held for investment		1,354,418			1,328,034			1,296,552			1,296,596			1,052,467
Less: Allowance for loan and lease losses		(16,236	)		(16,475	)		(16,738	)		(16,200	)		(12,762	)
Deferred loan and lease fees, net		(2,567	)		(2,172	)		(2,233	)		(2,332	)		(1,468	)
Total net loans and leases held for investment	$	1,335,615		$	1,309,387		$	1,277,581		$	1,278,064		$	1,038,237
Loans held for sale, at cost, which approximates market	$	—		$	—		$	—		$	—		$	—
Total loans and leases held for investment, net of deferred fees and costs	$	1,351,851		$	1,325,862		$	1,294,319		$	1,294,264		$	1,050,999
Percent of gross loans and leases held for investment
Real estate - mortgage		71.4	%		71.5	%		69.5	%		68.8	%		69.9	%
Real estate - construction		14.6	%		13.9	%		14.8	%		14.2	%		14.6	%
Commercial		11.3	%		11.7	%		12.0	%		12.9	%		12.1	%
Agricultural		0.6	%		0.6	%		1.1	%		1.3	%		0.0	%
Consumer		0.8	%		0.8	%		0.8	%		0.9	%		1.0	%
Leases receivable and other		1.3	%		1.5	%		1.8	%		1.9	%		2.4	%
		100.0	%		100.0	%		100.0	%		100.0	%		100.0	%

DEPOSITS

($ in thousands)

	At September 30, 2005				At December 31, 2004
	Amount		% of Deposits		Amount		% of Deposits
Non interest bearing deposits	$	496,787	31.5	%	$	485,193	32.3	%
Interest bearing deposits:
Interest bearing demand		248,013	15.7	%		256,650	17.1	%
Money market		292,154	18.6	%		262,957	17.5	%
Savings		173,138	11.0	%		179,578	12.0	%
Time, under $100,000		197,177	12.5	%		176,026	11.7	%
Time, $100,000 or more		168,478	10.7	%		139,655	9.4	%
Total interest bearing deposits		1,078,960	68.5	%		1,014,866	67.7	%
Total deposits	$	1,575,747	100.0	%	$	1,500,059	100.0	%