FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN 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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1. Name and Address of Reporting Person * LIEB PETER M   2. Issuer Name and Ticker or Trading Symbol AON CORP [AOC] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) EVP & General Counsel (Last) (First) (Middle) AON CORPORATION - CORPORATE LAW DEPT, 200 EAST RANDOLPH STREET, 8TH FLOOR 3. Date of Earliest Transaction (Month/Day/Year) 02/25/2011 (Street) CHICAGO, IL 60601 4. If Amendment, Date Original Filed(Month/Day/Year) 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 Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 02/25/2011   M(1)   1,708 A (1) 1,820.443 (8) D   Common Stock 02/25/2011   F(2)   538 D $ 52.49 1,282.443 (8) D

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

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Restricted Stock Unit Award (Right to Receive)

(3)

02/25/2011

M

1,708

02/25/2011

02/25/2011

Common Stock

1,708

$ 0

3,145

D

Phantom Stock

(4)

02/28/2011

A

610.01 (7)

(5)

(5)

Common Stock

610.01

$ 52.68

828.64 (6)

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
LIEB PETER M AON CORPORATION - CORPORATE LAW DEPT 200 EAST RANDOLPH STREET, 8TH FLOOR CHICAGO, IL 60601			EVP & General Counsel

Signatures

/s/ Jennifer L. Kraft - Jennifer L. Kraft pursuant to a power of attorney from Peter Lieb		03/01/2011
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(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)	Shares of common stock acquired upon the vesting of a restricted stock unit award.
(2)	Shares of common stock withheld by the issuer for the payment of withholding taxes in connection with the vesting of a restricted stock unit award.
(3)	The restricted stock unit award converts to shares of common stock on a 1-for-1 basis.
(4)	Each share of phantom stock acquired under the issuer's deferred compensation plan represents the right to receive one share of Aon common stock or the cash value thereof.
(5)	Shares of phantom stock are payable in cash in ten annual installments following the reporting person's retirement. Subject to the issuer's compliance procedures for its Section 16 reporting officers, the reporting person may transfer shares of common stock into an alternative investment account under the issuer's deferred compensation plan.
(6)	Includes shares acquired pursuant to dividend reinvestment.
(7)	This amount represents phantom shares acquired in connection with the deferral of a portion of the reporting person's short-term incentive for 2010 performance and a deferral of a portion of the reporting person's base salary.
(8)	Includes 112.443 shares held pursuant to the Aon employee stock purchase plan.

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