SPECIMEN
       COMMON STOCK                                 COMMON STOCK
          NUMBER                                       SHARES

US                 NATIONAL SCIENTIFIC CORPORATION

                                                   SEE REVERSE FOR
                                                 CERTAIN DEFINITIONS
                                                 CUSIP 637479 10 6
INCORPORATED UNDER THE LAWS
   OF THE STATE OF TEXAS

THIS CERTIFIES THAT
IS THE RECORD HOLDER OF

   FULLY PAID AND NON-ASSESSABLE SHARES OF PREFERRED STOCK, $.10 PAR VALUE OF

                        NATIONAL SCIENTIFIC CORPORATION

transferable  on the books of the  Corporation by the holder hereof in person or
by  duly  authorized  attorney  upon  surrender  of  this  Certificate  properly
endorsed.  This  Certificate  and the shares  represented  hereby are issued and
shall be subject to all of the provisions of the Articles of  Incorporation  and
By-laws of the Corporation,  each as from time to time amended,  copies of which
are on file with the Transfer  Agent,  to all of which the holder by  acceptance
hereof assents.
     This  Certificate  is not valid until  countersigned  and registered by the
Transfer Agent and Registrar.
     WITNESS the facsimile seal of the Corporation and the facsimile  signatures
of its duly authorized officers.

Dated:

/s/ Vernon Traylor Jr.                                 /s/ L. L. Ross
CORPORATE SECRETARY             [CORPORATE SEAL]       CHAIRMAN OF THE BOARD

COUNTERSIGNED AND REGISTERED:
U.S. STOCK TRANSFER CORPORATION
     TRANSFER AGENT AND REGISTRAR

By:
                         AUTHORIZED SIGNATURE
<PAGE>
     The Articles of  Incorporation  of the Corporation on file in the office of
the Secretary of State of Texas set forth (a) the aggregate number of shares and
the par value of each class of capital shares that the Corporation is authorized
to issue, together with the designations,  preferences, limitations and relative
rights of each such class;  (b) a statement of the authority vested in the Board
of Directors to establish  series and to fix and determine the variations in the
relative rights and  preferences  between any such series of the Preferred Stock
so established; (c) a denial of preemptive rights of the shareholders to acquire
additional,  unissued  or  treasury  shares of the  Corporation;  and (d) to the
record holder of this  certificate  without  charge upon written  request to the
corporation at its registered office.
     The  Corporation  shall furnish  without charge to each  stockholder who so
requests a statement  of the powers,  designations,  preferences  and  relative,
participating,  optional or other  special  rights of each class of stock of the
Corporation   or  series   thereof  and  the   qualifications,   limitations  or
restrictions of such preferences  and/or rights.  Such requests shall be made to
the Corporation's Secretary at the principal office of the Corporation.

     The following  abbreviations,  when used in the  inscription on the face of
this  certificate,  shall be  construed  as though they were written out in full
according to applicable laws or regulations:
<TABLE>
<CAPTION>
<S>                                          <C>
TEN COM   -- as tenants in common            UNIF GIFT MIN ACT - ................ Custodian for ..............
                                                                     (Cust.)                       (Minor)
TEN ENT   -- as tenants by the entireties                             under Uniform Gifts to Minors
                                                           Act ...............................................
JT TEN    -- as joint tenants with right                                       (State)
             of survivorship and not as      UNIF TRF MIN ACT - ................ Custodian (until age .......)
             tenants in common                                  ................. under Uniform Transfers
                                                                     (Minor)
                                                                to Minors Act ................................
                                                                                          (State)
                    Additional abbreviations may also be used though not in the above list.
</TABLE>

For value received ....................... hereby sell, assign and transfer unto

                    PLEASE INSERT SOCIAL SECURITY OR OTHER
                         IDENTIFYING NUMBER OF ASSIGNEE

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                    --------------------------------------
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   PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING ZIP CODE, OF ASSIGNEE

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                                                                          Shares
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of the common stock represented by the within Certificate, and do hereby
irrevocably constitute and appoint
                                                                        Attorney
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to transfer the said stock on the books of the within named Corporation,
with full power of substitution in the premises.

Dated ___________________________________
                                        X ______________________________________

                                        X ______________________________________
                                        NOTE: THE SIGNATURE(S) TO THIS
                                              ASSIGNMENT MUST CORRESPOND WITH
                                              THE NAME(S) AS WRITTEN UPON THE
                                              FACE OF THE CERTIFICATE IN EVERY
                                              PARTICULAR, WITHOUT ALTERATION
                                              OR ENLARGEMENT OR ANY CHANGE
                                              WHATEVER.
Signature(s) Guaranteed

By _____________________________________
THE SIGNATURE(S)SHOULD BE GUARANTEED BY
AN ELIGIBLE GUARANTOR INSTITUTION (BANKS,
STOCKBROKERS, SAVINGS AND LOAN ASSOCIATIONS
AND CREDIT UNIONS WITH MEMBERSHIP IN AN
APPROVED SIGNATURE GUARANTEE MEDALLION
PROGRAM), PURSUANT TO S.E.C. RULE 17Ad-15.