EXHIBIT A

                                                             Page 12 of 12 Pages

                                    EXHIBIT A

                             JOINT FILING AGREEMENT

                  The  undersigned  hereby agree that the  statement on Schedule
13G with respect to the Common Stock of Boston Life  Sciences,  Inc. dated as of
October  14,  1999 is,  and any  amendments  thereto  (including  amendments  on
Schedule  13D) signed by each of the  undersigned  shall be,  filed on behalf of
each of us pursuant to and in  accordance  with the  provisions of Rule 13d-1(f)
under the Securities Exchange Act of 1934.



Date:  October 14, 1999                XXXXX XXXXXXX STRATEGIC GROWTH FUND, L.P.

                                       By:    Xxxxx Xxxxxxx Capital, LLC
                                              Its General Partner

                                              By:    Xxxxx Xxxxxxx Partners, LLC
                                                     Its Member

                                                     By:     /S/ XXXX X. XXXXXX
                                                             -------------------
                                                             Xxxx X. Xxxxxx
                                                             Its Member


Date:  October 14, 1999                XXXXX XXXXXXX CAPITAL, LLC

                                       By:    Xxxxx Xxxxxxx Partners, LLC
                                              Its Member

                                              By:    /S/ XXXX X. XXXXXX
                                                     ---------------------------
                                                     Xxxx X. Xxxxxx
                                                     Its Member


Date:  October 14, 1999                XXXXX XXXXXXX STRATEGIC GROWTH FUND, LTD.

                                       By:    Xxxxx Xxxxxxx Asset Management LLC

                                              By:    Xxxxx Xxxxxxx, LLC
                                                     Its Member

                                                     By:     /S/ XXXX X. XXXXXX
                                                             -------------------
                                                             Xxxx X. Xxxxxx
                                                             Its Member


Date:  October 14, 1999                XXXXX XXXXXXX ASSET MANAGEMENT LLC

                                       By:    Xxxxx Xxxxxxx, LLC
                                              Its Member

                                                     By:     /S/ XXXX X. XXXXXX
                                                             -------------------
                                                             Xxxx X. Xxxxxx
                                                             Its Member