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                                                                       EXHIBIT 5

                                Bingham Dana LLP
                               150 Federal Street
                                Boston, MA 02110

                                          March 31, 1998


LeukoSite, Inc.
215 First Street
Cambridge, Massachusetts  02142

Dear Sir or Madam:

        We have acted as counsel for LeukoSite, Inc., a Delaware corporation
(the "Company"), in connection with the Company's Registration Statement on Form
S-8 to be filed with the Securities and Exchange Commission on March 31, 1998
(the "Registration Statement").

        The Registration Statement covers the registration of 150,000 shares of
common stock, $.01 par value per share, of the Company (the "Shares"), which are
to be issued by the Company pursuant to the LeukoSite, Inc., 1997 Employee Stock
Purchase Plan (the "Plan").

        We have reviewed the corporate proceedings of the Company with respect
to the authorization of the Plan and the issuance of the Shares thereunder. We
have also examined and relied upon originals or copies, certified or otherwise
identified or authenticated to our satisfaction, of such agreements,
instruments, corporate records, certificates, and other documents as we have
deemed necessary or appropriate as a basis for the opinions hereinafter
expressed. In our examination, we have assumed the genuineness of all
signatures, the conformity to the originals of all documents reviewed by us as
copies, the authenticity and completeness of all original documents reviewed by
us in original or copy form, and the legal competence of each individual
executing any document.

        We further assume that all Shares issued pursuant to the Plan will be 
issued in accordance with the terms of such Plan and that the purchase price of
the Shares will be greater than or equal to the par value per share of the
Shares.

        Subject to the limitations set forth below, we have made such
examination of law as we have deemed necessary for the purposes of this opinion.
This opinion is limited solely to the Delaware General Corporation Law as
applied by courts located in Delaware.


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        Based upon and subject to the foregoing, we are of the opinion that the
Shares, when issued and delivered pursuant to the Plan and against the payment
of the purchase price therefor, will be validly issued, fully paid, and
non-assessable.

        We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement.

                                         Very truly yours,



                                         /s/ BINGHAM DANA LLP