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Exhibit 99

Aon Announces Convertible Debt Offering

CHICAGO, IL—November 4, 2002—Aon Corporation (NYSE: AOC) today announced that it intends to offer in a private placement, subject to market and other conditions, $200 million in aggregate principal amount of convertible debentures due 2012 in an offering to qualified institutional buyers. The interest rate, conversion rate and offering price are to be determined by negotiations between Aon and the initial purchasers of the debentures. The offering is expected to take place on November 4, 2002. Aon intends to grant the initial purchasers a 13-day option to purchase an additional $30 million in aggregate principal amount of convertible debentures.

        Aon intends to use the net proceeds to repay short-term debt.

        Aon Corporation (www.aon.com) is a holding company that is comprised of a family of insurance brokerage, consulting and insurance underwriting subsidiaries.

This announcement is neither an offer to sell nor a solicitation to buy these securities. The securities will not be registered under the Securities Act of 1933, as amended (the "Securities Act"), or any state securities laws, and unless so registered, may not be offered or sold in the United States except pursuant to an exemption from the registration requirements of the Securities Act and applicable state laws. This press release may contain certain statements relating to future results, which are forward-looking statements as that term is defined in the Private Securities Litigation Reform Act of 1995. These forward-looking statements are subject to certain risks and uncertainties that could cause actual results to differ materially from either historical or anticipated results, depending on a variety of factors. Potential factors that could impact results include the general economic conditions in different countries around the world, fluctuations in global equity and fixed income markets, rating agency actions, the cost and availability of financing, the completion, cost and timing of the capital enhancement plan, changes in commercial property and casualty premium rates, the competitive environment, the actual cost of resolution of contingent liabilities and other loss contingencies, the ultimate impact of the business transformation plan, and the timing and resolution of related insurance and reinsurance issues relating to the events of September 11, 2001. Further information concerning the Company and its business, including factors that potentially could materially affect the Company's financial results, are contained in the Company's filings with the Securities and Exchange Commission.

-oOo-

Investor Contact:
Sean O'Neill
Vice President, Financial Relations
312-381-3983

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Exhibit 99