EXHIBIT 5.1

                                  OPINION OF COUNSEL


                                  December 17, 1997
                                           
Metra Biosystems, Inc.
265 N. Whisman Road
Mountain View, CA 94043-3911


    REGISTRATION STATEMENT ON FORM S-8
    ----------------------------------


Ladies and Gentlemen:

    We have examined the Registration Statement on Form S-8 (the 
"REGISTRATION STATEMENT") to be filed by Metra Biosystems, Inc. ("METRA") 
with the Securities and Exchange Commission (the "COMMISSION") on or about 
December 17, 1997 in connection with the registration under the Securities Act 
of 1933, as amended, of a total of 800,000 additional shares of Metra Common 
Stock reserved for issuance or issued under Metra's 1995 Stock Option Plan 
("METRA PLAN").  As Metra's legal counsel in connection with this 
transaction, we have examined the proceedings taken and are familiar with the 
proceedings proposed to be taken by Metra in connection with the sale and 
issuance of the foregoing shares under the Metra Plan (collectively, the 
"SHARES").

    It is our opinion that upon conclusion of the proceedings being taken or 
contemplated by us, as Metra's counsel, to be taken prior to the issuance of 
the Shares, and upon completion of the proceedings being taken in order to 
permit such transactions to be carried out in accordance with the securities 
laws of the various states where required, the Shares when issued and sold in 
the manner described in the Registration Statement will be legally and 
validly issued, fully paid and non-assessable.

    We consent to the use of this opinion as an exhibit to the Registration 
Statement and further consent to the use of our name wherever appearing in 
the Registration Statement, including the Prospectus constituting a part 
thereof, and in any amendment thereto.

                                       Very truly yours,

                                       VENTURE LAW GROUP
                                       A Professional Corporation


                                       /s/ VENTURE LAW GROUP