FORM 5 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b). Form 3 Holdings Reported Form 4 Transactions Reported

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 ANNUAL 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 * RYAN PATRICK G 2. Issuer Name and Ticker or Trading Symbol AON CORP [AOC] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) Chairman and CEO (Last) (First) (Middle) C/O AON CORPORATE LAW DEPARTMENT, 8TH FLOOR, 200 EAST RANDOLPH DRIVE 3. Statement for Issuer's Fiscal Year Ended (Month/Day/Year) 12/31/2004 (Street) CHICAGO, IL 60601 4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Reporting (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 at end of Issuer's Fiscal Year (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Amount (A) or (D) Price Common Stock 10/18/2004   G 650,000 (1) D $ 21.27 11,350,282 (2) (3) D   Common Stock 10/18/2004   G 650,000 (1) A $ 21.27 11,585,323 (2) I By Spouse Common Stock 10/22/2004   G 675,000 (1) D $ 19.8 10,675,282 (2) (3) D   Common Stock 10/22/2004   G 675,000 (1) A $ 19.8 12,260,323 (2) I By Spouse

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

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SEC 2270 (9-02)

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 at End of Issuer's Fiscal Year (Instr. 4)

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

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

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
RYAN PATRICK G C/O AON CORPORATE LAW DEPARTMENT 8TH FLOOR, 200 EAST RANDOLPH DRIVE CHICAGO, IL 60601	  X	Â	  Chairman and CEO	Â

Signatures

/s/ Patrick G. Ryan		02/14/2005
**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)	Gift by the living trust of the reporting person to the living trust of the reporting person's spouse.
(2)	The reporting person is also the indirect beneficial owner of the following securities: 386,915 by ESOP and Savings Plan; 583,942 by Spouse as Trustee.
(3)	Amount reported includes 2,593 shares received in connection with a distribution from an Employee Stock Ownership Plan (3,602 shares distributed less 1,009 shares withheld for taxes).

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