STOCK CERTIFICATE

INCORPORATED UNDER THE LAWS OF THE STATE OF DELAWARE

SERIES A CONVERTIBLE PREFERRED                                        

NUMBER                                                                    SHARES
MG

MEDCO GROUP
INCORPORATED

THIS CERTIFICATE IS TRANSFERABLE IN THE CITY OF NEW YORK
                                                                 SEE REVERSE FOR
                                                             CERTAIN DEFINITIONS

                                                               CUSIP 584053 30 0

This certifies that

is the owner of

FULLY PAID AND NON-ASSESSABLE SHARES OF THE PAR VALUE OF $.01 EACH 
OF SERIES A CONVERTIBLE PREFERRED STOCK OF

                                  MEDCO GROUP
                                  INCORPORATED
transferable on the books of the Corporation in person or by duly authorized
attorney on surrender of this certificate properly endorsed. This certificate
shall not be valid until countersigned and registered by the Transfer Agent and
Registrar. Witness the facsimile signatures of its duly authorized officers.

Dated: FEB 17, 1988

/s/                                          /s/
Secretary                                    President

                            MEDCO GROUP INCORPORATED
                                 CORPORATE SEAL
                                    DELAWARE
COUNTERSIGNED AND REGISTERED
AMERICAN STOCK TRANSFER COMPANY
(NEW YORK)
TRANSFER AGENT AND REGISTRAR
BY 
/S/            AUTHORIZED SIGNATURE
<PAGE>
                                  MEDCO GROUP
                                  INCORPORATED

     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.
TEN COM -- as tenants in common         UNIF GIFT MIN ACT -- .....Custodian.....
TEN ENT -- as tenants by the entireties                      (Cust)   (Minor)
JT TEN  -- as join tenants with right                       under Uniform Gifts
           of survivorship and not as                       to Minors Act.....
           tenants in common                                             (State)
           Additional abbreviations may also be used though not in the above
           list.

This  Corporation  will  furnish  without  charge  to  each  stockholder  who so
requests,  a  copy  of  the  designations,  powers,  preferences  and  relative,
participating, optional or other special rights of each class of stock or series
thereof and the qualifications,  limitations or restrictions of such preferences
and/or rights which are set forth in full in the  Certificate of  Incorporation,
as amended.


     FOR VALUE RECEIVED _______________________________ hereby sell, assign, and
transfer unto __________________________________________________________________
_____________________________________________ shares of the 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

                                       _________________________________________
                                                       Signature

                                       NOTICE:  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 whatever.

                                   The shares  represented  by this  certificate
                              have not been registered  under the Securities Act
                              of  1933.   The  shares  have  been  acquired  for
                              investment  and may not be  sold,  transferred  or
                              assigned   in   the   absence   of  an   effective
                              registration  statement for these shares under the
                              Securities  Act  of  1933  or an  opinion  of  the
                              Company's   counsel  that   registration   is  not
                              required under said Act.