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                                                                     EXHIBIT 8.1

                    PAUL, WEISS, RIFKIND, WHARTON & GARRISON
                           1285 AVENUE OF THE AMERICAS
                          NEW YORK, NEW YORK 10019-6064



                                                     August 9, 1999



Anteon Corporation
3211 Jermantown Road
Suite 700
Fairfax, VA 22030-2801

                  REGISTRATION STATEMENT ON FORM S-4

Ladies and Gentlemen:

                  In connection with the Registration Statement on Form S-4 (the
"Registration Statement") filed today by Anteon Corporation (the "Issuer"), a
Virginia corporation, with the Securities and Exchange Commission (the "SEC")
under the Securities Act of 1933, as amended (the "Act"), and the rules and
regulations under the Act (the "Rules"), we have been requested to render this
opinion. Capitalized terms used and not otherwise defined shall have the
meanings given those terms in the Registration Statement.

                  In this regard, we have reviewed copies of the Registration
Statement (including its exhibits) with respect to the offer by the Issuer to
exchange up to $100,000,000 in aggregate principal amount of its 12% Exchange
Senior Subordinated Notes due 2009 (the "Exchange Notes") for up to $100,000,000
in aggregate principal amount of its outstanding 12% Senior Subordinated Notes
due 2009 (the "Initial Notes"). We have also made those other investigations of
fact and law and have examined the originals, or copies authenticated to our
satisfaction, of those other





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Anteon Corporation
August 9, 1999
Page -2-


documents, records, certificates or other instruments as in our judgment are
necessary or appropriate to enable us to render our opinion.

                  Our opinion is limited to the Internal Revenue Code of 1986,
as amended (the "Code"), administrative rulings, judicial decisions, Treasury
regulations and other applicable authorities, all as in effect today. The
statutory provisions, regulations and interpretations upon which our opinion is
based are subject to change and those changes could apply retroactively. Any
change could affect the continuing validity of our opinion. We assume no
responsibility to advise you of any subsequent changes in existing law or facts,
nor do we assume any responsibility to update this opinion with respect to any
matters expressly stated in this letter, and no opinions are to be implied or
may be inferred beyond the matters expressly so stated.

                  Based upon and subject to the above, the legal matters and
conclusions stated in the Registration Statement under the heading "Certain
Federal Income Tax Considerations" constitute our opinion with respect to those
matters.

                  We hereby consent to the filing of this opinion as an exhibit
to the Registration Statement and to the reference to us under the heading
"Legal Matters" in the Prospectus included in the Registration Statement. In
giving this consent, we do not admit that we come within the category of persons
whose consent is required by the Act or the Rules.

                                    Very truly yours,

                                    /s/ Paul, Weiss, Rifkind, Wharton & Garrison
                                    PAUL, WEISS, RIFKIND, WHARTON & GARRISON








