EXHIBIT 5



June 18, 1999


Boston Life Sciences, Inc.
31 Newbury Street
Suite 300
Boston, Massachusetts   02116


       Re:  Boston Life Sciences, Inc. Amendment No. 1 to Registration Statement
            On Form S-3 (File No. 333-75175)


Gentlemen:

         We have acted as special counsel to Boston Life Sciences, Inc. (the
"Company") in connection with the registration under the Securities Act of 1933,
as amended, of 1,812,942 shares of common stock of the Company, par value $.01
per share (the "Shares"), proposed to be sold by certain Selling Stockholders
named in the Registration Statement on Form S-3 (the "Registration Statement").

         In rendering our opinion, we have reviewed and relied upon such
certificates, documents, corporate records, other instruments and
representations of officers of the Company as in our judgment are necessary or
appropriate to enable us to render the opinion expressed below. In giving this
opinion, we are assuming the authenticity of all instruments presented to us as
originals, the conformity with the originals of all instruments presented to us
as copies and the genuineness of all signatures.

         Based upon the foregoing, we are of the opinion that the Shares to be
sold by the Selling Stockholders have been duly authorized and, when duly
executed, delivered, issued and paid for, will be legally issued, fully paid and
nonassessable.

         We consent to the filing of this opinion as Exhibit 5 to the
Registration Statement with respect to the offering of the Shares and the
reference to the firm in the section of the Registration Statement entitled
"Legal Matters."

         This opinion is limited to the matters expressly stated herein. No
implied opinion may be inferred to extend this opinion beyond the matters
expressly stated herein. We do not undertake to advise you or anyone else of any
changes in the opinions expressed herein resulting from changes in law, changes
in facts or any other matters that hereafter might occur or be brought to our
attention.


                                   Very truly yours,

                                   /s/ Ballard Spahr Andrews & Ingersoll, LLP