Exhibit 5

              Letterhead of Arent Fox Kintner Plotkin & Kahn, PLLC

                                  May 13, 2002


The Board of Directors
GTSI Corp.
3901 Stonecroft Boulevard
Chantilly, Virginia 20151-1010

Gentlemen:

      We have acted as counsel to GTSI Corp. (the "Company") with respect to the
Company's Registration Statement on Form S-8, filed by the Company with the
Securities and Exchange Commission in connection with the registration under the
Securities Act of 1933, as amended, of 143,000 shares of Common Stock, par value
$.005 per share (the "Shares"), issued pursuant to Nonqualified Stock Option
Agreements between the Company and Johnny Wilkinson, Terri Allen, Scott
Friedlander, Christopher Pate, James Waldron and Lori Stallard (the "Stock
Option Agreements").

      As counsel to the Company, we have examined the Company's Certificate of
Incorporation, as amended, and such records, certificates and other documents of
the Company, as well as relevant statutes, regulations, published rulings and
such questions of law, as we considered necessary or appropriate for the purpose
of this opinion.

      We assume that, prior to the sale of any Shares to which the Registration
Statement relates, appropriate action will be taken to register and qualify such
Shares for sale, to the extent necessary, under any applicable state securities
laws.

      Based on the foregoing, we are of the opinion that the 143,000 Shares
subject to the Stock Option Agreements when issued or delivered and paid for in
accordance with the terms of the Stock Option Agreements, will be validly
issued, fully paid and nonassessable.

      We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to all references to our firm in the Registration
Statement. In giving this consent, we do not hereby admit that we come within
the category of persons whose consent is required under Section 7 of the
Securities Act of 1933, as amended, or the General Rules and Regulations
thereunder.

                                       Very truly yours,


                                       Arent Fox Kintner Plotkin & Kahn, PLLC