

                                                                       Exhibit 5


                                  June 30, 1998

Realty Information Group, Inc.
7475 Wisconsin Avenue
Bethesda, Maryland 20814

Ladies and Gentlemen:


     As counsel for Realty Information Group, Inc., a Delaware  corporation (the
"Company"),  we are familiar with the Company's  Registration  Statement on Form
S-1, first filed with the Securities and Exchange  Commission (the "Commission")
under the Securities Act of 1933, as amended (the "Act"),  on March 13, 1998, as
amended  by  Amendment  No.  1 to the  Registration  Statement  filed  with  the
Commission  on April 27, 1998,  Amendment  No. 2 to the  Registration  Statement
filed  with  the  Commission  on  May  14,  1998  and  Amendment  No.  3 to  the
Registration  Statement  filed with the  Commission  on June 12, 1998, as may be
further amended or supplemented  (collectively,  the "Registration  Statement"),
with respect to the offering (the  "Offering") of up to 2,500,000  shares of the
Company's Common Stock, $.01 par value, by the Company (the "Firm Shares"),  and
up to an additional  250,000  shares of Common Stock by the Company (the "Option
Shares") subject to an Underwriters' over-allotment option (the "Over- allotment
Option").  The Firm Shares and the Option  Shares are  collectively  referred to
hereafter as the "Shares."

     In connection  with the foregoing,  we have examined (i) the Certificate of
Incorporation  of the Company  filed with the  Secretary of State of Delaware on
February 2, 1998 (ii) the Restated  Certificate of Incorporation  filed with the
Secretary  of State of  Delaware  on March 13,  1998;  (iii) the  By-Laws of the
Company; (iv) the proposed form of Underwriting Agreement filed as an Exhibit to
the  Registration  Statement  with  respect  to the  Shares  (the  "Underwriting
Agreement");  (v) the form of stock certificate for common stock of the Company,
and  (vi)  such  records  of the  corporate  proceedings  of the  Company,  such
certificates of public officials and such other documents as we deemed necessary
to render this opinion.

<PAGE>
Realty Information Group, Inc.
June 30, 1998
Page 2

     Based on such examination and assumptions, we are of the opinion that:

     1. The Company is a corporation  duly  incorporated  and existing under the
laws of the State of Delaware.

     2. The Shares have been duly authorized and when sold,  issued and paid for
pursuant to the duly executed Underwriting  Agreement (in substantially the form
filed as an exhibit to the Registration Statement) will be validly issued, fully
paid and nonassessable.

     We  hereby  consent  to the  filing  of this  Opinion  as  Exhibit 5 to the
Registration  Statement and the reference to us in the Prospectus  which is part
of the Registration Statement.

                                    Very truly yours,

                                    WILMER, CUTLER & PICKERING

                                    By: /s/ Eric R. Markus
                                        --------------------------------
                                         Eric R. Markus, a partner



