CoStar Signs Multi-Year Renewal Agreement with Staubach Co.; Leading Corporate Services Firm Extends National Agreement for CoStar Leasing, Tenant Data.

Business Editors

BETHESDA, Md.--(BUSINESS WIRE)--April 23, 2002

CoStar Group Inc. (NASDAQ:CSGP), the leading information provider to the U.S. commercial real estate industry, has signed a long-term, national renewal agreement with The Staubach Co., a leading global real estate services firm specializing in tenant representation.

The agreement provides Staubach professionals in 25 markets with access to CoStar Property(TM), a complete inventory of office and industrial properties, and CoStar Tenant(R), a database of detailed tenant information for business-to-business prospecting and analysis.

"We're pleased to provide tools that help our customers provide the highest level of service to their clients," said Andrew C. Florance, CoStar Group's president & CEO. "Our commitment to provide valuable data and technology to our customers is reflected in our outstanding renewal record with prestigious real estate firms like The Staubach Co."

During the past six months, CoStar Group has signed major national renewal and expansion agreements with many of the leading commercial real estate services firms. More than 35,000 commercial real estate professionals rely on CoStar products to research leasing options, analyze market conditions, and accurately value properties in 50 markets nationwide.

About CoStar Group, Inc.

Headquartered in Bethesda, MD, CoStar Group, Inc. (NASDAQ:CSGP), is the leading provider of information services to the U.S. commercial real estate industry. CoStar's suite of products offers customers access to the most comprehensive, verified database of commercial real estate information in 50 U.S. markets. The company has approximately 800 employees and contractors nationally in 28 offices.

About The Staubach Company

The Staubach Company is a global, full-service real estate strategy and services firm that delivers innovative solutions for companies seeking office, retail and industrial space. The Staubach Company provides a complete range of services with nearly 1,200 professionals in North America, and access to more than 6,500 professionals in 41 countries worldwide, including coverage of Latin America through Herzog Staubach and Staubach SAC, and of Europe, Middle East, Africa and Asia through DTZ Staubach Tie Leung. Areas of expertise include site selection, acquisition and disposition, financing, design and construction, portfolio services and property management.

This news release includes "forward-looking statements," which involve many risks and uncertainties that could cause actual results to differ materially from these statements. Factors that could cause or contribute to such differences include, but are not limited to, those stated in CoStar's Form 10-K for the year ended December 31, 2001, under the heading "Risk Factors." All forward-looking statements are based on information available to CoStar on the date hereof, and CoStar assumes no obligation to update such statements.