Aon Corporation (NYSE: AOC) today announced the appointment of Bill Pieroni as global chief information officer.

(Logo: http://www.newscom.com/cgi-bin/prnh/20041215/CGW049LOGO )

Pieroni joins Aon from IBM, where he was head of that company's Global Insurance Industry practice. He has extensive technology and industry experience, working with insurance companies and other clients on complex information and technology issues.

Gregory C. Case, president and CEO, Aon Corporation, said, "Bill's appointment reflects the importance that we place on effective information technology services that support our operations while providing the best possible services to our clients. We are delighted to bring in an executive of Bill's experience and expertise, and we welcome him to the Aon management team."

Pieroni, whose appointment is effective Monday, June 20, will have responsibility for global Aon IT-related activities. He will be based in Chicago.

About Aon

Aon Corporation ( http://www.aon.com/ ) is a leading provider of risk management services, insurance and reinsurance brokerage, human capital and management consulting, and specialty insurance underwriting. There are 47,000 employees working in Aon's 500 offices in more than 120 countries. Backed by broad resources, industry knowledge and technical expertise, Aon professionals help a wide range of clients develop effective risk management and workforce productivity solutions.

  For more information, contact:
  Dave Van de Walle, Aon Corporation, +1.312.381.5028,
  dave_vandewalle@aon.com.

This press release contains certain statements related to future results, or states our intentions, beliefs and expectations or predictions for the future 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: general economic conditions in different countries in which we do business around the world, changes in global equity and fixed income markets that could affect the return on invested assets, fluctuations in exchange and interest rates that could influence revenue and expense, rating agency actions that could affect our ability to borrow funds, funding of our various pension plans, changes in the competitive environment, changes in commercial property and casualty markets and commercial premium rates that could impact revenues, changes in revenues and earnings due to the elimination of contingent commissions, other uncertainties surrounding a new compensation model, the impact of regulatory investigations brought by state attorneys general and state insurance regulators related to our compensation arrangements with underwriters and related issues, the impact of class actions and individual lawsuits including client class actions, securities class actions, derivative actions, and ERISA class actions, the cost of resolution of other contingent liabilities and loss contingencies, and the difference in ultimate paid claims in our underwriting companies from actuarial estimates. Further information concerning the Company and its business, including factors that potentially could materially affect the Company's financial results, is contained in the Company's filings with the Securities and Exchange Commission.

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SOURCE: Aon Corporation

CONTACT: Dave Van de Walle, Aon Corporation, +1-312-381-5028,
dave_vandewalle@aon.com

Web site: http://www.aon.com/