WOODBURN AND WEDGE
Attorneys and Counselors of Law
Sierra Plaza
6100 Neil Road, Suite 500
Reno, Nevada 89511-1149
Telephone (775) 688-3000
Facsimile (775) 688-3088


                                 July 28, 2000


Cyanotech Corporation
73-4460 Queen Kaahumanu Hwy.
Suite 102
Kailua-Kona, Hawaii 96740

        RE:     Cyanotech Corporation
                Registration Statement Form S-3

Ladies and Gentlemen:

     We have acted as special Nevada counsel to Cyanotech Corporation,  a Nevada
corporation  (the  "Company"),  in connection  with the  registration  under the
Securities Act of 1933, as amended,  of 833,333  shares of the Company's  Common
Stock,  $0.005  par value per share  (the  "Conversion  Shares")  issuable  upon
conversion  of  $1,250,000  principal  amount  of  6%  Convertible  Subordinated
Debentures  due  April 30,  2002 (the  "Debentures")  and  83,334  shares of the
Company's  Common Stock,  $0.005 par value per share (the "Warrant  Shares" and,
together with the Conversion  Shares,  the "Shares"),  issuable upon exercise of
Warrants issued to the Placement Agent for the Debentures.

     In connection with this opinion, we have examined the following documents:

     A. The Debentures;

     B. The Warrant;

     C. Restated  Articles of Incorporation of the Company,  as amended to date,
     on file with the Nevada Secretary of State;

     D. Bylaws of the Company, as amended to date;

Cyanotech Corporation
July 28, 2000
Page 2



     E. Resolutions  adopted  by  the Board  of Directors of the Company
     pertaining to the Shares; and

     F. The  Registration  Statement  on Form S-3 as filed  today by the
     Company  with  the  Securities and Exchange Commission covering the  Shares
     (the "Registration Statement"), including the Prospectus (the "Prospectus")
     constituting a part of such Registration Statement.

     In  addition,  we have  examined  such other  documents  as we have  deemed
necessary or appropriate as a basis for the opinions hereinafter expressed.

     As  to  certain  questions  of  fact,  we  have  relied,   without  further
investigation,  upon certificates of governmental authorities and of officers of
the Company.  Additionally, we have assumed that the signatures on all documents
examined by us are genuine,  that all documents submitted to us as originals are
authentic and that all  documents  submitted to us as copies or as facsimiles of
copies or originals,  conform with the originals,  which assumptions we have not
independently verified.

     Based upon the foregoing and the  examination of such legal  authorities as
we  have  deemed  relevant,  and  subject  to  the  qualifications  and  further
assumptions set forth below, we are of the opinion that:

     1.  The  Company is a duly incorporated  and existing corporation under the
laws of the State of Nevada.

     2.  The  Shares  to  which the Registration Statement and Prospectus relate
are  duly  authorized  and,  when  issued  upon  conversion of the Debentures or
exercise  of  the  warrants,  as  described  in  the  Registration Statement and
Prospectus, will be validly issued, fully paid and non-assessable.

     The foregoing  opinion is limited to the matters expressly set forth herein
and no opinion may be implied or inferred beyond the matters  expressly  stated.
We disclaim any obligation to update this letter for events  occurring after the
date of this letter, or as a result of knowledge acquired by us after that date,
including  changes in any of the statutory or  decisional  law after the date of
this  letter.  We are  members of the bar of the State of Nevada.  We express no
opinion as to the effect and  application of any United States federal law, rule
or  regulation or any  securities  or blue sky laws of any state,  including the
State of Nevada.  We are not opining on, and assume no responsibility as to, the
applicability to or the effect


Cyanotech Corporation
July 28, 2000
Page 3


on any of the matters covered herein of the  laws  of  any  other  jurisdiction,
other  than  the laws of Nevada as presently in effect.

     We  hereby  consent  to the  use  of  this  opinion  as an  exhibit  to the
Registration  Statement  and to the  reference  to our  name  in the  Prospectus
constituting  a part of such  Registration  Statement  under the heading  "Legal
Matters." In giving such  consent,  we do not thereby  admit that we come within
the  category  of persons  whose  consent  is  required  under  Section 7 of the
Securities  Act of  1933,  as  amended,  or the  rules  and  regulations  of the
Securities and Exchange Commission thereunder.

                                        Very truly yours,

                                        WOODBURN AND WEDGE


                                        By:/s/ Kirk S. Schumacher
                                           -----------------------------
                                           Kirk S. Schumacher