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                                                                    Exhibit 5.1


                    **SUBJECT TO OPINION COMMITTEE CLEARANCE**


                                Bingham McCutchen LLP
                                 150 Federal Street
                           Boston, Massachusetts 02110-1726
                                 tel: 617-951-8000
                                  fax: 617-951-8736

                                                __________________________, 2003

TolerRx, Inc.
300 Technology Square
Cambridge, MA 02139

Dear Ladies and Gentlemen:

     We have acted as counsel for TolerRx, Inc., a Delaware corporation (the
"Company"), in connection with the registration under the Securities Act of
1933, as amended (the "Act"), of 4,700,000 shares and up to an additional
705,000 shares which may be offered by the Company in order to cover
over-allotments, if any, of common stock, par value $0.001 per share of the
Company (the "Shares"), pursuant to a Registration Statement on Form S-1 (as
amended, the "Registration Statement"), initially filed with the Securities
Exchange Commission on August 26, 2003.

     We have reviewed the corporate proceedings of the Company with respect
to the authorization of the issuance of the Shares.  We have also examined
and relied upon originals or copies, certified or otherwise identified or
authenticated to our satisfaction, of such corporate records, instruments,
agreements or other documents of the Company, and certificates of officers of
the Company as to certain factual matters, and have made such investigation
of law and have discussed with officers and representatives of the Company
such questions of fact, 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 have also assumed that an Underwriting Agreement substantially in the
form of Exhibit 1.1 to the Registration Statement, by and among the Company
and the underwriters named therein (the "Underwriting Agreement"), will have
been duly executed and delivered pursuant to the authorizing resolutions of
the Board of Directors

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of the Company and that the Shares will be sold and transferred only upon the
payment therefor as provided in the Underwriting Agreement.  We have further
assumed that the registration requirements of the Act and all applicable
requirements of state laws regulating the sale of securities will have been
duly satisfied.

     This opinion is limited solely to the Delaware General Corporation Law
as applied by courts located in Delaware.

     Based upon and subject to the foregoing, we are of the opinion that the
Shares have been duly authorized, and when delivered and paid for in
accordance with the provisions of the Underwriting Agreement, 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 and to the reference to this firm under the
heading "Legal matters" in the Registration Statement.

                                                  Very truly yours,



                                                  BINGHAM McCUTCHEN LLP