Exhibit 5.1


October 19, 2001



Lightbridge, Inc.
67 South Bedford Street
Burlington, Massachusetts  01803


Ladies and Gentlemen:

         We have acted as counsel for Lightbridge, Inc., a Delaware corporation
(the "Company"), in connection with the preparation and filing with the
Securities and Exchange Commission under the Securities Act of 1933, as amended,
of a Registration Statement on Form S-8 (the "Registration Statement") relating
to the offering by the Company of 200,000 shares (the "Shares") of its common
stock, $.01 par value, issuable pursuant to the Lightbridge, Inc. 1996 Employee
Stock Purchase Plan (the "Plan").

         In arriving at the opinions expressed below, we have examined and
relied on the following documents:

           (i)      the Registration Statement;

           (ii)     the Plan;

           (iii)    the Certificate of Incorporation and By-Laws of the Company;
                    and

           (iv)     a written consent adopted by the Board of Directors as of
                    August 1, 2001.

         In addition, we have examined and relied on the originals or copies
certified or otherwise identified to our satisfaction of all such records,
documents and instruments of the Company and such other persons, and we have
made such investigations of law, as we have deemed appropriate as a basis for
the opinions expressed below.

         We express no opinion other than as to the General Corporation Law of
the State of Delaware.

         Based upon the foregoing, we are of the opinion that:

1. The Company has the corporate power necessary for the issuance of the Shares
under the Plan, as contemplated by the Registration Statement.





October 19, 2001
Page 2



2. The Shares have been duly authorized and, when issued against payment of the
agreed consideration therefor in accordance with the Plan, will be validly
issued, fully paid and non-assessable.

         We consent to the filing of this opinion as Exhibit 5.1 to the
Registration Statement.

                                                Very truly yours,

                                                FOLEY, HOAG & ELIOT LLP


                                                By:    /s/ Alexander H. Pyle
                                                    ----------------------------
                                                          a Partner