Exhibit 5
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                                                     January 27, 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 a 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 6,305,934  shares (the "Shares") of Common Stock, par value $.01 per
share (the "Common  Stock"),  which  includes  4,603,453  shares  issuable  upon
conversion  of 4,000  shares  of the  Company's  Series D  Preferred  Stock  and
1,627,481  shares issuable upon  conversion of the Company's  Series E Preferred
Stock  (collectively,  the  "Conversion  Shares"),  par value $.01 per share and
75,000  shares  issuable  upon  exercise of  outstanding  warrants (the "Warrant
Shares"). The Warrant Shares and the Conversion Shares are collectively referred
to herein as the "Shares."

          In  connection  with the  foregoing,  we have  examined  originals  or
copies,  satisfactory to us, of the Company's (i) Certificate of  Incorporation,
(ii) By-laws and (iii) resolutions of the Company's board of directors.  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.

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         Based upon and subject to the foregoing, we are of the opinion that the
Shares,  when issued upon  conversion of the Series D and E Preferred  Stock and
exercise of the Warrants, as applicable,  will be validly issued, fully paid and
non-assessable.

         We hereby  consent to the  filing of this  opinion as an exhibit to the
Registration Statement.


                                         Very truly yours,

                                         /s/ Parker Chapin Flattau & Klimpl, LLP

                                         PARKER CHAPIN FLATTAU & KLIMPL, LLP


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