FORM 3
        	UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES
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                      	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	                      	

1. Name and Address of Reporting Person *

MOHONEY DENNIS L	2. Date of Event Requiring Statement (MM/DD/YYYY)
11/21/2003 
	3. Issuer Name and Ticker or Trading Symbol

AON CORP [AOC]	
(Last)        (First)        (Middle)

AON CORPORATION - CORPORATE LAW DEPT, 200 EAST RANDOLPH STREET, 8TH FLOOR	4. Relationship of Reporting Person(s) to Issuer (Check all applicable)

_____ Director                            _____ 10% Owner
___ X ___ Officer (give title below)          _____ Other (specify below)
Aon Limited - Chairman/CEO /	
(Street)

CHICAGO, IL 60601       

(City)              (State)              (Zip)	5. If Amendment, Date Original Filed (MM/DD/YYYY)

	6. Individual or Joint/Group Filing (Check Applicable Line)

_ X _ Form filed by One Reporting Person
___ Form filed by More than One Reporting Person	

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  	31724  	D  	 	

Table II - Derivative Securities Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities)	
1. Title of Derivate Security
(Instr. 4)	2. Date Exercisable and Expiration Date
(MM/DD/YYYY)	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				
Stock Award (Right to Receive)  	  (1) (2)	2/16/2007  	Common Stock  	45000  	$0  	D  	 	
Stock Award (Right to Receive)  	  (1) (3)	9/1/2008  	Common Stock  	75000  	$0  	D  	 	
Employee Stock Option (Right to Buy)  	  (4)	7/18/2007  	Common Stock  	45000  	$35.3542  	D  	 	
Employee Stock Option (Right to Buy)  	  (5) (6)	2/11/2010  	Common Stock  	100000  	$23.9375  	D  	 	
Employee Stock Option (Right to Buy)  	  (5) (7)	3/16/2011  	Common Stock  	50000  	$34.555  	D  	 	
Employee Stock Option (Right to Buy)  	  (5) (8)	4/22/2012  	Common Stock  	50000  	$36.875  	D  	 	
Employee Stock Option (Right to Buy)  	  (5) (9)	3/20/2013  	Common Stock  	100000  	$19.700  	D  	 	

Explanation of Responses:	
(  1) 	Awards will vest in accordance with the Aon Stock Incentive Plan as follows: 20% of the awards will vest on each of the third and tenth anniversaries of the date of grant, and 10% of the awards will vest on each of the fourth through ninth anniversaries of the date of grant.	
(  2) 	The date of grant was January 16, 1997. As of the date of this report, 22,500 award shares have vested.	
(  3) 	The date of grant was August 1, 1998. As of the date of this report, 30,000 award shares have vested.	
(  4) 	The date of grant was July 18, 1997. As of the date of this report, 45,000 options have vested.	
(  5) 	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.	
(  6) 	The date of grant was February 11, 2000. As of the date of this report, 67,000 options have vested.	
(  7) 	The date of grant was March 16, 2001. As of the date of this report, 16,500 options have vested.	
(  8) 	The date of grant was April 22, 2002.	
(  9) 	The date of grant was March 20, 2003.	

Reporting Owners	
Reporting Owner Name / Address	Relationships	
	Director	10% Owner	Officer	Other	
MOHONEY DENNIS L
AON CORPORATION - CORPORATE LAW DEPT
200 EAST RANDOLPH STREET, 8TH FLOOR
CHICAGO, IL 60601			Aon Limited - Chairman/CEO		

Signatures		
/s/ Jennifer L. Kraft - Jennifer L. Kraft pursuant to a power of attorney from Dennis L. Mahoney		12/1/2003	
** Signature of Reporting Person		Date

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.	
*	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).	
Note:	File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.	
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number.	
 
Exhibit 24
POWER OF ATTORNEY
I, Dennis L. Mahoney ('Grantor'), hereby confirm, constitute and appoint each of Jennifer L. Kraft and Richard E. Barry, severally and not jointly, signing singly, as the true and lawful attorney- in-fact of Grantor to:
1. execute for and on behalf of Grantor, in Grantor's capacity as an officer, for purposes of Section 16 of the Securities Exchange Act of 1934, as amended (the 'Exchange Act'), of Aon Corporation (the 'Company'), Forms 3, 4 and 5, including but not limited to any amendments thereto, in accordance with Section 16(a) of the Exchange Act, and the rules promulgated thereunder, which may be necessary or desirable as a result of Grantor's ownership of or transaction in securities of Aon Corporation; and
2. do and perform any and all acts for and on behalf of Grantor which may be necessary or desirable to complete and execute any such Form 3, 4 or 5 or any amendments thereto, and timely file such form with the United States Securities and Exchange Commission (the 'SEC') and any other entity or person.
Grantor hereby grants to each such attorney-in-fact full power and authority to do and perform any and every act and thing whatsoever requisite, necessary or proper to be done in the exercise of any of the rights and powers herein granted, as fully to all intents and purposes as the undersigned might or could do if personally present, with full power of substitution or revocation, hereby ratifying and confirming all that such attorney-in-fact, or such attorney-in-fact's substitute or substitutes, shall lawfully do or cause to be done by virtue of this power of attorney and the rights and powers herein granted. Grantor acknowledges that the foregoing attorneys-in-fact, in serving in such capacity at the request of Grantor, are not assuming, nor is the Company assuming, any of Grantor's responsibilities to comply with Section 16 of the Exchange Act.
This Power of Attorney shall be effective on the date set forth below and shall continue in full force and effect until the date on which Grantor shall cease to be subject to Section 16 of the Exchange Act and the rules promulgated thereunder or until such earlier date on which written notification executed by Grantor is filed with the SEC expressly revoking this Power of Attorney.
Grantor hereby revokes all prior powers of attorney that are in effect and filed with the SEC.
IN WITNESS WHEREOF, Grantor has caused this Power of Attorney to be executed as of this 1st day of December, 2003.

Signature:   /s/ Dennis L. Mahoney
                Dennis L. Mahoney