CANCELLATION OF UCT OPTION AGREEMENT


     The undersigned,  NDA Cinical Trial Services, Inc. ("NDA") and shareholders
representing  a majority  of the  outstanding  shares of  capital  stock of NDA,
hereby  agree,  for good and  valuable  consideration,  the  receipt of which is
hereby  acknowledged,  that  the  certain  Option  Agreement  among  NDA and its
shareholders,  Unilabs Cinical Trials, Ltd. and UniHolding Corp. dated September
27, 1995 is hereby cancelled, null and void as of the date hereof.

Dated:    August 26, 1996

                                        NDA CLINICAL TRIAL SERVICES, INC.

                                        By:  /s/ Ronald Gambardella
                                        Name:    Ronald Gambardella

                                        POLY VENTURES II

                                        By:  /s/ Robert Brill
                                        Name:    Robert Brill

                                        LONG ISLAND VENTURE FUND

                                        By:  /s/ Paul Lowell
                                        Name:    Paul Lowell


                                        By:  /s/ David Deutsch
                                        Name:    David Deutsch

                                        By:  /s/ Ronald Gamberdella
                                        Name:    Ronald Gamberdella