UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549-5546

         DIVISION OF
CORPORATION FINANCE

Mail Stop 5546
								December 6, 2005

Via US Mail and Facsimile

Patrick Ryan
Chairman and CEO
Aon Corporation
200 E. Randolph Street
Chicago, IL  60601

      Re:	Aon Corporation
      Form 10-K for the Fiscal Year Ended December 31, 2004
		Filed June 2, 2005
      File No. 001-07933

Dear Mr. Ryan:

      We have reviewed your response letter dated November 15,
2005
and have the following comment.  At this juncture, we are asking
you
to provide us with supplemental information, so that we may better
understand your disclosure.  Please be as detailed as necessary in
your response.

      We welcome any questions you may have about our comment or
on
any other aspect of our review.  Feel free to call us at the
telephone numbers listed at the end of this letter.

General

1. We note your response to prior comment two from our letter
dated
October 18, 2005.   Please provide a summary of the Compliance
Department`s report as soon as practicable following its
completion.
Address for us the materiality of your subsidiaries` activities
relating to Iran, and whether those activities constitute a
material
investment risk to your security holders, in light of the impact
your
status as a company whose subsidiaries do business in and/or with
a
U.S.-designated terrorist-sponsoring state may have upon your
reputation and share value.  Provide us with both your conclusion
and
your underlying analysis.  In your response, please discuss
investor
concern regarding investment in companies that do business with
such
states, as evidenced by the Arizona and Louisiana legislation
referenced in our October 18 letter.

      Please understand that we may have additional comments after
reviewing your response to our comment.  Please file your response
letter on EDGAR.

      Please contact James Lopez at (202) 551-3536 if you have any
questions about the comments or our review.  You may also contact
me
at (202) 551-3470.

								Sincerely,


								Cecilia D. Blye, Chief
								Office of Global Security
Risk

cc: 	Jeff Riedler
		Assistant Director
		Division of Corporation Finance
Mr. Patrick Ryan
Aon Corporation
December 6, 2005
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