SPECIMEN
                        NATIONAL SCIENTIFIC CORPORATION
               INCORPORATED UNDER THE LAWS OF THE STATE OF TEXAS

          NUMBER                                       SHARES
                                                   SEE REVERSE FOR
                                                 CERTAIN DEFINITIONS
THIS CERTIFIES THAT
IS THE OWNER OF

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

transferable only 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 is not valid until  countersigned  and registered by
the Transfer Agent and Registrar.

     IN WITNESS  WHEREOF,  the  Corporation  has caused this  Certificate  to be
signed by the  facsimile  signatures of its duly  authorized  officers and to be
sealed with the facsimile seal of the Corporation.

Dated:

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

COUNTERSIGNED:
CORPORATE STOCK TRANSFER, INC.
370 - 17th Street, Suite 2350, Denver, Colorado 80202

By: ___________________________________________
Transfer Agent and Registrar Authorized Officer
<PAGE>
                        NATIONAL SCIENTIFIC CORPORATION
                         CORPORATE STOCK TRANSFER, INC.
                      TRANSFER FEE: $15.00 PER CERTIFICATE
--------------------------------------------------------------------------------
     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
JT TEN    -- as joint tenants with right of                Act of ............................................
             survivorship and not as tenants                                    (State)
             in common
                    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
                    --------------------------------------

                    --------------------------------------
               Please print or type name and address of assignee
 ................................................................................
 ................................................................................
 ................................................................................
 ......................................................................... Shares
of the Preferred Stock represented by the within Certificate and do hereby
irrevocably constitute and appoint
 ................................................................................
 ................................................................................
      Attorney to transfer the said stock on the books of the within named
         Corporation, with full power of substitution in the premises.

Dated ...................... 19 ..........
SIGNATURE GUARANTEED:                   X ______________________________________
                                        X ______________________________________
     THE SIGNATURE TO THIS  ASSIGNMENT  MUST CORRESPOND WITH THE NAME AS WRITTEN
UPON THE FACE OF THIS  CERTIFICATE IN EVERY  PARTICULAR,  WITHOUT  ALTERATION OR
ENLARGEMENT OR ANY CHANGE WHATSOEVER.  THE SIGNATURE(S) MUST 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 RULE  17Ad-15  UNDER THE  SECURITIES
EXCHANGE ACT OF 1934, AS AMENDED.