-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
 MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen
 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 J4FRwOIdlTGQ+KteUTaNfyexU5zYA4seQ4JCVV5W6taRmWhxJ4IJJJd2wCj6mKjW
 1Sm5fgOWI493jvHzTbAQ2w==

<SEC-DOCUMENT>0001057352-08-000048.txt : 20080529
<SEC-HEADER>0001057352-08-000048.hdr.sgml : 20080529
<ACCEPTANCE-DATETIME>20080529112813
ACCESSION NUMBER:		0001057352-08-000048
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20080528
FILED AS OF DATE:		20080529
DATE AS OF CHANGE:		20080529

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			COSTAR GROUP INC
		CENTRAL INDEX KEY:			0001057352
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-BUSINESS SERVICES, NEC [7389]
		IRS NUMBER:				522091509
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		2 BETHESDA METRO CENTER
		STREET 2:		10TH FLOOR
		CITY:			BETHESDA
		STATE:			MD
		ZIP:			20814
		BUSINESS PHONE:		3012158300

	MAIL ADDRESS:	
		STREET 1:		2 BETHESDA METRO CENTER
		STREET 2:		10TH FLOOR
		CITY:			BETHESDA
		STATE:			MD
		ZIP:			20814

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Radecki Brian J
		CENTRAL INDEX KEY:			0001402193

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-24531
		FILM NUMBER:		08865271

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		301-215-8300

	MAIL ADDRESS:	
		STREET 1:		C/O COSTAR GROUP, INC.
		STREET 2:		2 BETHESDA METRO CENTER, 10TH FLOOR
		CITY:			BETHESDA
		STATE:			MD
		ZIP:			20814
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
</DOCUMENT>
</SUBMISSION>