ADMINISTAFF AND AON ENTERPRISE INSURANCE SERVICES TO FORM STRATEGIC ALLIANCE

HOUSTON – January 19, 2000 – Administaff, Inc. (NYSE: ASF), a leading Professional Employer Organization (PEO), and Aon Enterprise Insurance Services, Inc., a leading provider of insurance services to small businesses, today announced the signing of a letter of intent for the formation of a strategic alliance, under which Aon will offer an array of property and casualty insurance products to Administaff clients through a co-branded web site and its new state-of-the-art Client Service Center. Aon Enterprise is part of Aon Corporation (NYSE: AOC), a Fortune 500 holding company that comprises a family of insurance brokerage, consulting, and insurance underwriting subsidiaries.

Through Aon Enterprise, Administaff clients will have access to Aon’s expedited underwriting and economies not usually available to small business owners. Aon will offer insurance products that include property and casualty, directors and officers, general liability, automobile, professional liability, and umbrella liability coverage to qualified Administaff clients. Administaff anticipates receiving revenues stemming from the alliance through Administaff Enterprises, Inc., its licensed insurance agency.

"We are extremely pleased to add Aon Enterprise to our growing network of best-of-class service providers," said Paul J. Sarvadi, Administaff president and chief executive officer. "Our relationship will enable Aon to offer Administaff clients excellent business insurance coverages quickly, easily and affordably through our eCommerce portal."

Michael Garner, president and chief executive officer of Aon Enterprise, commented, "Aon Enterprise has pioneered a new, more efficient approach to meeting the insurance needs of the small business community. We are proud to have this opportunity to work with Administaff and are confident its clients will appreciate the economy and simplicity of this new service model and what it can mean to their business success."

Administaff Background

Administaff provides small and medium-sized businesses with a comprehensive Personnel Management System that includes benefits and payroll administration, medical and workers’ compensation insurance programs, personnel records management, employer liability management, employee recruiting and selection, performance management, and training and development services. With 1998 revenues of $1.7 billion, Administaff ranks number 765 on the Fortune 1000 list. The company also was named in 1999 to Fortune magazine’s list of "America’s Most Admired Companies," the Forbes Platinum 400 list of the best-performing big companies in the U.S., and the InformationWeek 500 list as one of the top users of information technology. The company currently has 25 offices in 15 major markets and serves clients and worksite employees throughout the United States. For additional information, visit the company’s web site at www.administaff.com.

Aon Enterprise Background

Aon Enterprise is a dynamic facility specifically created for the small commercial business segment. Aon Enterprise has partnered with premier insurance companies to provide comprehensive and competitive product lines.

Aon Enterprise is supported by service from a cutting-edge Client Service Center that has been designed to reduce costs, improve response time, and streamline service by:

• Replacing traditional processing techniques with state-of-the-art technology.
• Reducing duplicate handling between broker and insurer by having the Aon Enterprise
• staff underwrite and process many transactions.
• Reducing expenses by leveraging relationships with selected insurers.
• Consolidating back-room services into one central location.

Aon Enterprise was created in response to three major insurance market developments:

• The expanding availability of technology and its ability to enhance the customer's service experience.
• The changing insurance marketplace; consolidations and deregulation, in particular, allow new entrants into the fold.
• The expanding service requirements and expectations of commercial insurance buyers in an increasingly demanding Internet-driven marketplace.

For more information on Aon Enterprise Insurance Services, Inc. and the family of Aon companies, visit the company’s web site at www.aon.com.

(Note: The statements contained in this press release that are not historical facts are forward-looking statements that involve a number of risks and uncertainties. Therefore, the actual results of future events described in such forward-looking statements could differ materially from those stated in such forward-looking statements. Among the factors that could cause actual results to differ materially are: (i) regulatory and tax developments; (ii) changes in Administaff’s direct costs and operating expenses; (iii) the effectiveness of Administaff’s sales and marketing efforts, including its marketing agreement with American Express, American Express’ ability to set qualified appointments and Administaff’s ability to convert those appointments into sales; (iv) the estimated costs and effectiveness of capital projects and investments in technology and infrastructure; (v) Administaff’s ability to effectively implement its eBusiness strategy, including identifying and reaching agreements with strategic alliance partners, timely rollout of and attraction of clients and worksite employees to its eCommerce portal, effective generation of revenues from eBusiness initiatives and unanticipated development costs of eBusiness initiatives; (vi) changes in the competitive environments in the PEO industry; and (vii) the effectiveness and estimated costs of Administaff’s Year 2000 conversion and contingency plans. These factors are described in further detail in Administaff’s filings with the Securities and Exchange Commission.)