EXHIBIT 4.3

THE SALE AND ISSUANCE OF THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT
BEEN  REGISTERED  UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE  "SECURITIES
ACT"), OR UNDER THE SECURITIES LAW OF ANY STATE OR OTHER  JURISDICTION.  NEITHER
THIS  SECURITY NOR ANY INTEREST OR  PARTICIPATION  HEREIN MAY BE OFFERED,  SOLD,
ASSIGNED, TRANSFERRED,  PLEDGED, ENCUMBERED,  HYPOTHECATED OR OTHERWISE DISPOSED
OF, UNLESS PURSUANT TO AN EFFECTIVE  REGISTRATION STATEMENT UNDER THE SECURITIES
ACT OR PURSUANT TO A  TRANSACTION  THAT IS EXEMPT FROM,  OR NOT SUBJECT TO, SUCH
REGISTRATION UNDER THE SECURITIES ACT OR ANY APPLICABLE STATE SECURITIES LAWS.


                          COMMON STOCK PURCHASE WARRANT


                              XYBERNAUT CORPORATION


                             EXPIRES OCTOBER 24, 2002


No.:                                                   Number of Shares: 10,000
Date of Issuance:  October 25, 1999


                  1.   Issuance.   In   consideration   of  good  and   valuable
consideration,  the  receipt  of  which  is  hereby  acknowledged  by  Xybernaut
Corporation, a Delaware corporation (the "Company"), E. Dell Smith or registered
assigns  (the  "Holder"),  is hereby  granted  the right to purchase at any time
until  5:00 P.M.,  New York City time,  on  October  24,  2002 (the  "Expiration
Date"),  ten  thousand  (10,000)  fully  paid and  nonassessable  shares  of the
Company's  Common  Stock,  par value $.01 per share (the  "Common  Stock") at an
initial exercise price of $2.00 per share (the "Exercise Price").

                  2. Exercise of Warrants.  This Warrant is exercisable in whole
or in part at the Exercise  Price per share of Common Stock  payable  hereunder,
payable in cash or by certified or official bank check.  Upon  surrender of this
Warrant  Certificate  with the annexed  Notice of Exercise  Form duly  executed,
together  with  payment of the  Exercise  Price for the  shares of Common  Stock
purchased, the Holder shall be entitled to receive a certificate or certificates
for the shares of Common Stock so purchased.

                  3.  Reservation  of Shares.  The Company hereby agrees that at
all times during the term of this  Warrant  there shall be reserved for issuance
upon exercise of this Warrant
<PAGE>

such number of shares of its Common Stock as shall be required for issuance upon
exercise of this Warrant (the "Warrant Shares").

                  4. Mutilation or Loss of Warrant.  Upon receipt by the Company
of evidence satisfactory to it of the loss, theft,  destruction or mutilation of
this  Warrant,  and (in the  case of  loss,  theft or  destruction)  receipt  of
reasonably  satisfactory  indemnification,  and (in the case of mutilation) upon
surrender and cancellation of this Warrant, the Company will execute and deliver
a new  Warrant of like tenor and date and any such lost,  stolen,  destroyed  or
mutilated Warrant shall thereupon become void.

                  5.  Rights of the  Holder.  The Holder  shall  not,  by virtue
hereof, be entitled to any rights of a stockholder in the Company, either at law
or equity,  and the rights of the Holder are limited to those  expressed in this
Warrant and in the Consulting Agreement between the Company and Libra Finance SA
pursuant  to  which  this  Warrant  was  originally   issued  (the   "Consulting
Agreement") and are not enforceable against the Company except to the extent set
forth herein and therein.

                  6. Transfer to Comply with the  Securities  Act;  Registration
Rights.

                         6.1 This  Warrant  has not been  registered  under  the
Securities  Act of 1933,  as  amended,  (the  "Act") and has been  issued to the
Holder  for  investment  and not with a view to the  distribution  of either the
Warrant or the  Warrant  Shares.  Neither  this  Warrant  nor any of the Warrant
Shares or any other  security  issued or issuable  upon exercise of this Warrant
may  be  offered,  sold,  transferred,  pledged,  encumbered,   hypothecated  or
otherwise  disposed of in the  absence of an  effective  registration  statement
under the Act relating to such security or an opinion of counsel satisfactory to
the Company that  registration  is not required under the Act. Each  certificate
for the Warrant,  the Warrant Shares and any other  security  issued or issuable
upon exercise of this Warrant  shall  contain a legend on the face  thereof,  in
form and substance  satisfactory  to counsel for the Company,  setting forth the
restrictions on transfer contained in this Section.

                         6.2 The Company  hereby grants to the Holder  piggyback
registration  rights  with  respect to the Warrant  Shares  which  rights  shall
commence after the date of issuance of this Warrant. In the event the Company is
filing  a  registration  statement  for  itself  or on  behalf  of  any  of  its
shareholders  at any time after the date  hereof,  the Company  shall notify the
Holder in writing  reasonably  in advance of such  filing (but at least five (5)
business days) and give the Holder the opportunity to include all or any portion
of  the  Warrant  Shares  (whether  or not  previously  issued,  to  the  extent
permissible under the Act or any regulation  promulgated  thereunder).  Upon the
Holder's  notification that the Holder desires to have all or any portion of the
Warrant Shares included in such  registration,  the Company shall, at no cost or
expense to the  Holder,  include or cause to be  included  in such  registration
statement the Warrant  Shares so identified  by the Holder,  provided,  however,
that if, in the opinion of the Company's  managing  underwriter or underwriters,
if any, for such offering,  the inclusion of the Warrant  Shares,  when added to
the securities  being  registered by the Company or any selling  stockholder(s),
will
<PAGE>

exceed the maximum amount of the Company's  securities  that can be marketed (x)
at a price reasonably related to their then current market value, or (y) without
materially  and adversely  affecting the entire terms of the offering,  then the
number of shares to be included  in such  offering  shall be  reduced,  and such
shares shall be excluded from such offering in a number deemed necessary by such
managing  underwriter  or  underwriters,  based  upon and  subject to a pro rata
reduction of the number of Warrant Shares the Holder of such securities proposed
to include therein.

                  7.  Notices.  Any notice or other  communication  required  or
permitted  hereunder  shall be in  writing  and shall be  delivered  personally,
telegraphed,  telexed,  sent by  facsimile  transmission  or sent by  certified,
registered or express mail,  postage  pre-paid.  Any such notice shall be deemed
given when so delivered  personally,  telegraphed,  telexed or sent by facsimile
transmission,  or, if  mailed,  two (2) days  after the date of  deposit  in the
United States mails, as follows:

(1)      if the to Company, to:

                                    Xybernaut Corporation
                                    12701 Fair Lakes Circle
                                    Suite 550
                                    Fairfax, Virginia 22033
                                    Attn: Chief Financial Officer
                                    Fax No.:  (703) 631-3903

(2)      if to the Holder, to:

                                    E. Del Smith and Company, Inc.
                                    1130 Connecticut Avenue, N.W.
                                    Suite 650
                                    Washington, DC 20036
                                    Attn:  E. Del Smith
                                    Fax No.:

Any party may be  notice  given in  accordance  with this  Section  to the other
parties designate another address or person for receipt of notices hereunder.

                  8. Supplements and Amendments;  Whole Agreement.  This Warrant
may be amended or  supplemented  only by an instrument in writing  signed by the
parties hereto. This Warrant of even date herewith and the Consulting  Agreement
contain the full understanding of the parties hereto with respect to the subject
matter  hereof  and  thereof  and  there  are  no  representations,  warranties,
agreements or understandings other than expressly contained herein and therein.

<PAGE>

                  9.  Governing  Law.  This  Warrant  shall  be  deemed  to be a
contract made under the laws of the State of New York and for all purposes shall
be  governed  by and  construed  in  accordance  with  the  laws of  such  State
applicable to contracts to be made and performed entirely within such State.

                  10. Descriptive Headings.  Descriptive headings of the several
Sections of this Warrant are inserted for convenience only and shall not control
or affect the meaning or construction of any of the provisions hereof.


         IN WITNESS WHEREOF, the parties hereto have executed this Warrant as of
October 25, 1999.


                            XYBERNAUT CORPORATION



                            By:_______________________________________
                               Name: Steven A. Newman
                               Title: Vice Chairman

Attest:

----------------------------

----------------------------
Chief Administrative Officer



<PAGE>




                          NOTICE OF EXERCISE OF WARRANT

         The  undersigned  hereby  irrevocably  elects to  exercise  the  right,
represented by the Warrant Certificate dated as of __________, 2000, to purchase
__________  shares of the Common Stock,  par value $.01 per share,  of Xybernaut
Corporation  and tenders  herewith  payment in accordance with Section 1 of said
Common Stock Purchase Warrant.

         Please deliver the stock certificate to:





Dated:______________________




                                          By:__________________________________