1

                                                                       EXHIBIT 5

                             LYNCH, CHAPPELL & ALSUP
                           A PROFESSIONAL CORPORATION
                                    ATTORNEYS
                              THE SUMMIT, SUITE 700
                              300 NORTH MARIENFELD
                              MIDLAND, TEXAS 79701
                            TELEPHONE: (915) 683-3351
                            FACSIMILE: (915) 683-8346


                                 March 27, 2001


Tom Brown, Inc.
508 W. Wall, Suite 500
Midland, Texas  79701

            Re: Tom Brown, Inc. 1993 Stock Option Plan; Sale of up to
                900,000 additional Shares of Common Stock

Gentlemen:

         We have acted as counsel to Tom Brown, Inc., a Delaware corporation
(the "Company"), in connection with the proposed issuance and sale by the
Company of up to 900,000 additional shares of Common Stock, $.10 par value
("Common Stock"), of the Company pursuant to the exercise of stock options
granted or to be granted by the Company under the Company's 1993 Stock Option
Plan (the "Plan"), as further described in a Registration Statement on Form S-8
filed by the Company with the Securities and Exchange Commission (herein
referred to as the "Registration Statement").

         We have made such inquiries and examined such documents as we have
considered necessary or appropriate for the purpose of giving the opinions
hereinafter set forth. We have assumed the genuineness and authenticity of all
signatures on all original documents, the authenticity of all documents
submitted to us as originals, the conformity to originals of all documents
submitted to us as copies and the due authorization, execution, delivery or
recordation of all documents where due authorization, execution or recordation
are prerequisites to the effectiveness thereof.


   2

March 27, 2001
Page 2


         Based upon the foregoing, and having regard for such legal
considerations as we deem relevant, we are of the opinion that the Plan has been
duly and validly authorized and adopted, and the 900,000 shares of Common Stock
that may be issued and sold by the Company from time to time upon the exercise
of stock options granted or to be granted in accordance with the Company's Plan
will, upon issuance and delivery against payment therefor, be legally issued,
fully paid and nonassessable.

         We hereby consent to the filing of this opinion with the Securities and
Exchange Commission as an exhibit to the Registration Statement and to the
statements made regarding our Firm and to the use of our name under the heading
"Item 5. Interests of Named Experts and Counsel" in the Registration Statement.

                                                 Very truly yours,

                                                 LYNCH, CHAPPELL & ALSUP,
                                                 a Professional Corporation

                                                 By: /s/ Thomas W. Ortloff
                                                     -----------------------
                                                       Thomas W. Ortloff