8-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the
Securities Exchange Act of 1934

Date of report (Date of earliest event reported): March 19, 2008

Aon Corporation
(Exact Name of Registrant as Specified in Charter)

Delaware	1-7933	36-3051915
(State or Other Jurisdiction of Incorporation)	(Commission File Number)	(IRS Employer Identification No.)

200 East Randolph Street, Chicago, Illinois	60601
(Address of Principal Executive Offices)	(Zip Code)

Registrant’s telephone number, including area code: (312) 381-1000

Not Applicable
(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

oWritten communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

oSoliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

oPre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

oPre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 5.02.Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

(b)On March 19, 2008, Aon Corporation (the “Company”) issued a press release (the “Press Release”) announcing that Patrick G. Ryan, Executive Chairman, plans to retire from the Company as of August 1, 2008.

A copy of the Press Release is attached hereto as Exhibit 99.1 and is incorporated herein by reference.

Item 9.01.              Financial Statements and Exhibits.

(a) - (c)   Not applicable.

(d)           Exhibits:

Exhibit Number	Description of Exhibit
99.1	Press Release issued by the Company on March 19, 2008.

2

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

	Aon CORPORATION
	By:	/s/ Jennifer L. Kraft
		Jennifer L. Kraft
Date: March 21, 2008		Vice President, Associate General Counsel and Secretary

3

EXHIBIT INDEX

Exhibit Number	Description of Exhibit
99.1	Press Release issued by the Company on March 19, 2008.

4

EX-99.1

News from Aon

Media Contact

David Prosperi

Vice President, Global Public Relations

312.381.2485

David_Prosperi@aon.com

For immediate release

Patrick G. Ryan Announces Intention to Retire from Aon

CHICAGO, March 19, 2008 - Patrick G. Ryan, founder and executive chairman of Aon Corporation, today announced he intends to retire from Aon effective August 1, 2008. Aon is the world’s largest insurance and reinsurance intermediary, and a global leader in human capital consulting.

Ryan commented, “The transition to a new management team under the sound leadership of Greg Case is complete. Aon is extremely well-positioned for continued growth and success. After 41 years as CEO and three years as Executive Chairman, it is time to retire from active involvement. I will of course continue to be a dedicated and interested shareholder.”

Ryan, 70, founded Aon, which has its origin in a small insurance agency he started in 1964. That agency eventually became Ryan Insurance, a firm focused on a strategy of providing advice, consulting services and distribution of insurance products to the automotive industry.

In 1978, Ryan Insurance purchased the insurance brokerage subsidiaries of Esmark Corporation, expanding into risk management solutions for commercial and industrial clients. In 1982, following a merger with Combined Insurance Company of America, the company acquired Rollins Burdick Hunter, then the 7th largest insurance broker in the world. The company continued to expand through organic growth and acquisition, and in 1987 changed its name to Aon Corporation. Through the late 1980s and into the 1990s the company continued its strategy of acquisition and became a global leader in the insurance/reinsurance brokerage and human capital consulting fields. Today Aon operates with more than 500 offices in 120 countries generating revenues in excess of $7 billion.

Gregory C. Case, president and chief executive officer of Aon Corporation, said, “Pat Ryan is one of the great visionaries and leaders in the insurance industry. His vision of creating a truly global company in the fields of risk management and human capital consulting became a reality that serves thousands of clients around the world every day. He has been enormously helpful to me and the senior leadership team over the past three years, and I thank him for his support and guidance.”

Andrew J. McKenna, lead director of Aon’s Board of Directors, noted, “Not only has Pat distinguished himself through the founding and success of Aon, he and his wife Shirley continue to take leadership roles in many civic, cultural, educational and philanthropic endeavors. The Chicago area is a better place to live and work because of the many contributions they have made. On behalf of the Aon Board of Directors, we want to thank Pat for his outstanding leadership.”

Ryan will continue as chairman of the Board of Trustees of Northwestern University, and as chairman & chief executive officer of Chicago 2016, the effort to bring the 2016 Olympic and Paralympic games to Chicago.

About Aon

Aon Corporation (NYSE:AOC) is the leading global provider of risk management services, insurance and reinsurance brokerage, human capital and management consulting, and specialty insurance underwriting. Through its 43,000 professionals worldwide, Aon readily delivers distinctive client value via innovative and effective risk management and workforce productivity solutions. Our industry-leading global resources, technical expertise and industry knowledge are delivered locally through more than 500 offices in more than 120 countries. Aon was ranked by A.M. Best as the number one global insurance brokerage in 2007 based on brokerage revenues, and voted best insurance intermediary, best reinsurance intermediary, and best employee benefits consulting firm in 2007 by the readers of Business Insurance. For more information on Aon, log onto www.aon.com.

2