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EXHIBIT 23.1
CONSENT OF ERNST & YOUNG, INDEPENDENT AUDITORS
We consent to the incorporation by reference in the Registration Statement
(Form S-8 No. 333-______) pertaining to the CoStar Group, Inc. 1998 Stock
Incentive Plan, as Amended, of our report dated March 1, 2000, with respect to
the consolidated financial statements of CoStar Group, Inc. included in its
Annual Report (Form 10-K) for the year ended December 31, 1999, filed with the
Securities and Exchange Commission.
/s/ Ernst & Young LLP
McLean, Virginia
September 13, 2000
