Exhibit 5.1

                OPINION OF JENKENS & GILCHRIST PARKER CHAPIN LLP



                                                   December 30, 2004


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,  for the
registration for resale by the selling stockholders listed therein of 18,334,772
shares of Common Stock,  par value $.01 per share (the "Common  Stock"),  of the
Company.  Of the 18,334,772 shares of Common Stock being  registered,  9,167,386
shares are currently  issued and outstanding (the "Shares") and 9,167,386 shares
are  issuable  upon  exercise  of  warrants  by the  selling  stockholders  (the
"Warrants").

         In connection with the foregoing, we have examined originals or copies,
satisfactory to us, of the Company's (i) Certificate of  Incorporation  and (ii)
Bylaws.  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  and the  compliance  with
applicable  state  securities  laws,  we are of the opinion  that (i)  9,167,386
shares of Common Stock currently  outstanding are validly issued, fully paid and
nonassessable  and (ii) the remaining  9,167,386  shares of Common Stock, if and
when issued upon  surrender  of the Warrants and exercise and the payment of the
exercise price as provided in the Warrants,  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 the reference made to us under the caption "Legal
Matters" in the prospectus constituting part of the Registration Statement.

                                           Very truly yours,


                                       /s/ JENKENS & GILCHRIST PARKER CHAPIN LLP
                                           Jenkens & Gilchrist Parker Chapin LLP