FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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(Print or Type Responses)

1. Name and Address of Reporting Person *   Harmer Peter 2. Date of Event Requiring Statement (Month/Day/Year) 03/16/2007 3. Issuer Name and Ticker or Trading Symbol AON CORP [AOC] (Last) (First) (Middle) C/O AON CORPORATE LAW DEPT, 200 EAST RANDOLPH STREET, 8TH FL 4. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) Aon Limited - CEO 5. If Amendment, Date Original Filed(Month/Day/Year) (Street) CHICAGO, IL 60601 6. Individual or Joint/Group Filing(Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Beneficially Owned

1.Title of Security (Instr. 4) 2. Amount of Securities Beneficially Owned (Instr. 4) 3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5) 4. Nature of Indirect Beneficial Ownership (Instr. 5) Common Stock 1,740 (1) D Â

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.			SEC 1473 (7-02)
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Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Employee Stock Option (Right to Buy)	  (2)(3)	02/11/2010	Common Stock	4,500	$ 23.9375	D	Â
Employee Stock Option (Right to Buy)	  (2)(4)	04/20/2011	Common Stock	10,000	$ 32.525	D	Â
Employee Stock Option (Right to Buy)	  (2)(5)	04/22/2012	Common Stock	10,000	$ 36.875	D	Â
Employee Stock Option (Right to Buy)	  (2)(6)	03/20/2013	Common Stock	10,000	$ 19.7	D	Â
Employee Stock Option (Right to Buy)	  (7)(8)	07/16/2014	Common Stock	11,000	$ 27.03	D	Â
Employee Stock Option (Right to Buy)	  (9)(10)	03/16/2012	Common Stock	18,206	$ 41.195	D	Â
Restricted Stock Unit Award (Right to Receive)	  (11)(12)	07/16/2009	Common Stock	8,250	$ (13)	D	Â
Restricted Stock Unit Award (Right to Receive)	  (14)(15)	03/17/2008	Common Stock	6,608	$ (13)	D	Â
Restricted Stock Unit Award (Right to Receive)	  (14)(16)	03/16/2009	Common Stock	2,580	$ (13)	D	Â
Employee Stock Option (Right to Buy)	  (17)(18)	03/15/2013	Common Stock	30,324	$ 37.1	D	Â
Restricted Stock Unit Award (Right to Receive)	  (14)(18)	03/15/2010	Common Stock	3,193	$ (13)	D	Â

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Harmer Peter C/O AON CORPORATE LAW DEPT 200 EAST RANDOLPH STREET, 8TH FL CHICAGO, IL 60601	Â	Â	  Aon Limited - CEO	Â

Signatures

/s/ Jennifer L. Kraft - by Jennifer L. Kraft pursuant to a power of attorney from Peter Harmer		03/19/2007
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 5(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	Includes 1,978 shares held in the Australian ESPP.
(2)	Options will vest in accordance with the Aon Stock Incentive Plan as follows: 33% of the options will vest on each of the second and fourth anniversaries of the date of grant, and 34% of the options will vest on the third anniversary of the date of grant.
(3)	The date of grant was February 11, 2000.
(4)	The date of grant was April 20, 2001.
(5)	The date of grant was April 22, 2002.
(6)	The date of grant was March 20, 2003.
(7)	Options will vest in accordance with the Aon Stock Incentive Plan as follows: 100% of the options will vest on the fifth anniversary of the date of grant.
(8)	The date of grant was July 16, 2004.
(9)	Options will vest in accordance with the Aon Stock Incentive Plan as follows: 33.34% of the options will vest on the first anniversary of the date of grant, and 33.33% of the options will vest on the second and third anniversaries of the date of grant.
(10)	The date of grant was March 16, 2006.
(11)	Awards will vest in accordance with the Aon Stock Incentive Plan as follows: 100% of the awards will vest on the fifth anniversary of the date of grant.
(12)	The date of grant was July 16, 2004.
(13)	The restricted stock unit award converts to shares of common stock on a 1-for-1 basis.
(14)	Awards will vest in accordance with the Aon Stock Incentive Plan as follows: 22.25% of the awards will vest on each of the first and second anniversaries of the date of grant, and 55.50% of the awards will vest on the third anniversary of the date of grant.
(15)	The date of grant was March 17, 2005.
(16)	The date of grant was March 16, 2006.
(17)	Options will vest in accordance with the terms of the Aon Stock Incentive Plan as follows: one-third of the options will vest on each of the first through third anniversaries of the date of grant.
(18)	The date of grant was March 15, 2007.

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