EXHIBIT 5.1



May 31, 2000

Bioject Medical Technologies, Inc.
7620 S.W. Bridgeport Road
Portland, OR  97224

Gentlemen and Ladies:

We are delivering this opinion in connection with the Registration  Statement on
Form S-8 (the "Registration  Statement") of Bioject Medical  Technologies,  Inc.
(the  "Company") to be filed with the Securities and Exchange  Commission  under
the Securities Act of 1933, as amended (the "Securities  Act"),  with respect to
an  aggregate  of 300,000  shares,  without  par value,  of common  stock of the
Company  (the  "Shares")  to  be  offered   pursuant  to  the  Bioject   Medical
Technologies, Inc. 1992 Stock Incentive Plan (the "Plan") to participants in the
Plan (the "Participants").

We have  examined  and are  familiar  with  originals  or copies,  certified  or
otherwise identified to our satisfaction,  of such documents,  corporate records
and other  instruments  relating to the  incorporation of the Company and to the
authorization and issuance of the Shares,  and have made such  investigations of
law, as we have deemed necessary and advisable.

Based upon the  foregoing  and having due regard for such legal  questions as we
have  deemed  relevant,  we are of the  opinion  that the Shares  have been duly
authorized,  and, when issued, delivered and sold by the Company and paid for by
the  Participants,  pursuant  to the terms of the  Plan,  will  constitute  duly
authorized,  legally issued, fully paid and nonassessable shares of common stock
of the Company.

We  hereby  consent  to  the  filing  of  this  opinion  as an  exhibit  to  the
Registration  Statement  referred to above,  and to the reference to our firm in
the Prospectus constituting a part of the Registration Statement

Very truly yours,


/s/ Dorsey & Whitney LLP