Exhibit 5.1








                                 April 25, 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  resale of up to  300,000  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