EXHIBIT 5.1







                                December 4, 2001




BioMarin Pharmaceutical Inc.
371 Bel Marin Keys Boulevard, Suite 210
Novato, CA 94949

      Re:   Registration Statement on Form S-3

Ladies and Gentlemen:

            We are furnishing this opinion of counsel to BioMarin Pharmaceutical
Inc., a Delaware corporation (the "Company"), for filing as Exhibit 5.1 to the
Registration Statement on Form S-3 (the "Registration Statement") to be filed by
the Company with the Securities and Exchange Commission under the Securities Act
of 1933, as amended, relating to the sale and issuance of up to 6,900,000 shares
(the "Shares") of the Company's Common Stock, $.001 par value per share ("Common
Stock").

            In connection with this opinion, we have examined and relied upon
the Registration Statement and related prospectus, the Company's Amended and
Restated Certificate of Incorporation, the Company's Restated Bylaws, and the
originals or copies certified to our satisfaction of such documents, records,
certificates, memoranda and other instruments as in our judgment are necessary
or appropriate to enable us to render the opinion expressed below. We have
assumed the genuineness and authenticity of all documents submitted to us as
copies thereof, and the due execution and delivery of all documents where due
execution and delivery are a prerequisite to the effectiveness thereof. We have
also assumed that, at the time the Shares are issued, the Company will have
sufficient authorized and unissued shares of Common Stock.

            On the basis of the foregoing, and in reliance thereon, we are of
the opinion that the Shares, when issued and paid for in accordance with the
Registration Statement, will be validly issued, fully paid, and nonassessable.

            We express no opinion with respect to the applicability or effect of
the laws of any jurisdiction other than the Delaware General Corporation Law, as
in effect as of the date hereof.



BioMarin Pharmaceutical Inc.
December 4, 2001
Page 2


            We hereby consent to being named as counsel to the Company in the
Registration Statement, to the references therein to our firm under the caption
"Legal matters" and to the inclusion of this opinion as an exhibit to the
Registration Statement. This opinion is rendered to you in connection with the
Registration Statement and is solely for your benefit. This opinion may not be
relied upon by you for any other purpose, or relied upon by any other person,
firm or other entity for any purpose, without our prior written consent.

                                       Very truly yours,




                             /s/ Paul, Hastings, Janofsky & Walker LLP
                               PAUL, HASTINGS, JANOFSKY & WALKER LLP