JOINT FILING AGREEMENT This will confirm the agreement by and among all the undersigned that the Schedule 13D filed on or about this date (the "Schedule 13D") with respect to the beneficial ownership by the undersigned of shares of common stock, par...

                                                                       EXHIBIT 3


                             JOINT FILING AGREEMENT

         This will confirm the agreement by and among all the undersigned that
the Schedule 13D filed on or about this date (the "Schedule 13D") with respect
to the beneficial ownership by the undersigned of shares of common stock, par
value $.01 per share, of Cistron Biotechnology, Inc., a Delaware corporation, is
being, and any and all amendments thereto may be, filed on behalf of each of the
undersigned.

         This Agreement may be executed in counterparts, each of which will be
deemed an original, but all of which together shall constitute one and the same
instrument.

Dated as of:  Xxxxx 00, 0000


                                  XXXXXXXX GROUP PLC

                                  By: /s/ Xxxxx Xxxxx
                                     ----------------------
                                     Xxxxx Xxxxx
                                     Director

                                  CGP ACQUISITION CORP.

                                  By: /s/ Xxxxx Xxxxx
                                     ----------------------
                                     Xxxxx Xxxxx
                                     President