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                                                                     EXHIBIT 5.1

                          OPINION OF PARKER CHAPIN LLP

                                               July 7, 2000

Xybernaut Corporation
12701 Fair Lakes Circle
Fairfax, Virginia  22033

Gentlemen:

          We have acted as counsel to Xybernaut Corporation, a Delaware
corporation (the "Company"), in connection with the Registration Statement on
Form S-3 (the "Registration Statement") being filed with the Securities and
Exchange Commission under the Securities Act of 1933, as amended, relating to
the offering of 625,023 shares (the "Shares") of Common Stock, par value $.01
per share (the "Common Stock").

          In connection with the foregoing, we have examined originals or
copies, satisfactory to us, of the Company's (i) Certificate of Incorporation
and (ii) By-laws. We have also reviewed such other matters of law and examined
and relied upon all such corporate records, agreements, certificates and other
documents as we have deemed relevant and necessary as a basis for the opinion
hereinafter expressed. In such examination, we have assumed the genuineness of
all signatures, the authenticity of all documents submitted to us as originals
and the conformity with the original documents of all documents submitted to us
as copies or facsimiles. As to any facts material to such opinion, we have, to
the extent that relevant facts were not independently established by us, relied
on certificates of public officials and certificates of officers or other
representatives of the Company.

          Based upon and subject to the foregoing, we are of the opinion that
the Shares have been validly issued and are fully paid and non-assessable.

          We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to the reference made to us under the caption "Legal
Matters" in the prospectus constituting part of the Registration Statement.

                                                 Very truly yours,

                                                 /s/ Parker Chapin LLP

                                                 PARKER CHAPIN LLP