EXHIBIT 5.1


                          [Letterhead of Ropes & Gray]



                                                              July 2, 2002



StemCells, Inc.
3155 Porter Drive
Palo Alto, CA  94304

Ladies and Gentlemen:

         This opinion is furnished to you in connection with a registration
statement on Form S-3 (the "Registration Statement"), filed with the Securities
and Exchange Commission under the Securities Act of 1933, as amended (the "1933
Act"), for the registration of 15,000,000 shares of Common Stock, $0.01 par
value (the "Shares"), of StemCells, Inc., a Delaware corporation (the
"Company"). The Shares may be issued from time to time on a delayed or
continuous basis pursuant to Rule 415 under the 1933 Act.

         We have acted as counsel for the Company in connection with its
proposed issuance and sale of the Shares. For purposes of this opinion, we have
examined and relied upon such documents, records, certificates and other
instruments as we have deemed necessary.

         We express no opinion as to the applicability of, compliance with, or
effect of Federal law or the law of any jurisdiction other than The Commonwealth
of Massachusetts and the corporate laws of the State of Delaware.

     Based upon and subject to the foregoing, and assuming that:

o    the Registration Statement and any amendments thereto (including
     post-effective amendments) will have become effective and comply with all
     applicable laws;
o    the Registration Statement will be effective and will comply with all
     applicable laws at the time the Shares are offered or issued as
     contemplated by the Registration Statement;
o    a Prospectus Supplement will have been prepared and filed with the
     Securities and Exchange Commission describing the Shares offered
     thereby and will comply with all applicable laws;




o    all Shares will be issued and sold in compliance with applicable federal
     and state securities laws and in the manner stated in the Registration
     Statement and the appropriate Prospectus Supplement;
o    a definitive purchase, underwriting, or similar agreement with respect to
     any Shares offered or issued will have been duly authorized and validly
     executed and delivered by the Company and the other parties thereto,

         when both (A) the Company's Board of Directors has taken all necessary
corporate action to approve the issuance of and the terms of the offering of the
Shares and related matters and (B) certificates representing the Shares have
been duly executed, countersigned, registered, and delivered either (i) in
accordance with the applicable definitive purchase, underwriting, or similar
agreement approved by the Company's Board of Directors or authorized officers of
the Company upon payment of the consideration therefor (not less than the par
value of the Shares) provided for therein or (ii) upon conversion or exercise of
any other security, in accordance with the terms of such security or the
instrument governing such security providing for such conversion or exercise as
approved by the Company's Board of Directors, for the consideration approved by
the Company's Board of Directors (not less than the par value of the Shares),
then the Shares will be validly issued, fully paid, and non-assessable.

         We hereby consent to your filing a form of this opinion as an exhibit
to the Registration Statement and to the use of our name therein and in the
related prospectus under the caption "Legal Matters." It is understood that this
opinion is to be used only in connection with the offer and sale of the Shares
while the Registration Statement is in effect.


                                 Very truly yours,

                                 /s/ Ropes & Gray

                                 Ropes & Gray