Exhibit 5.1

                                  May 21, 2001

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

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 resale of up to  5,621,960  shares (the
"Shares") of its Common Stock, $.001 par value per share.

     We have  examined the  certificate  of  incorporation  and bylaws,  each as
amended to date,  of the  Company,  and the  originals,  or copies  certified or
otherwise identified, of records of corporate action of the Company as furnished
to us by the Company, certificates of public officials and of representatives of
the Company, and such other instruments and documents as we deemed necessary, as
a basis for the opinions  hereinafter  expressed.  In such  examination  we have
assumed the  genuineness of all  signatures,  the  authenticity of all corporate
records  and other  documents  submitted  to us and the  conformity  to original
documents submitted to us as certified or photostatic copies.

     Based  upon  our  examination  as  aforesaid,  and  in  reliance  upon  our
examination   of  such   questions  of  law  as  we  deem  relevant   under  the
circumstances,  we are of the opinion that the Shares, when purchased and issued
as described in 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.

     We hereby  consent to the filing of this  opinion of counsel as Exhibit 5.1
to the Registration Statement and to the reference to our firm under the caption
"Legal Matters."
                                Very truly yours,

                                /s/ PAUL, HASTINGS, JANOFSKY & WALKER LLP