Exhibit 5(a)

                                [L&W Letterhead]

                                  June 19, 1997



Algos Pharmaceutical Corporation
Collingwood Plaza
4900 Route 33
Neptune, New Jersey 07753

            Re:  Registration Statement on Form S-8 with respect to 887,270
                 shares of Common Stock, par value $.01 per share
                 ------------------------------------------------------------


Ladies and Gentlemen:

                  In  connection  with  the  preparation  and  filing  by  Algos
Pharmaceutical  Corporation  (the  "Company")  with the  Securities and Exchange
Commission (the "Commission")  under the Securities Act of 1933, as amended (the
"Act"), of a Registration  Statement on Form S-8 (the "Registration  Statement")
relating  to the  issuance  by the  Company of 887,270  shares of the  Company's
Common  Stock,  par value $.01 per share (the  "Shares"),  pursuant to the Algos
Pharmaceutical  Corporation  1994 Stock  Option Plan,  the Algos  Pharmaceutical
Corporation  1996 Stock Option Plan,  and the Algos  Pharmaceutical  Corporation
1996 Non-Employee  Director Stock Option Plan (collectively,  the "Plans"),  you
have requested our opinion with respect to the matters set forth below.

                  In our  capacity  as your  counsel  in  connection  with  such
registration,  we are  familiar  with the  proceedings  taken and proposed to be
taken by the Company in connection with the authorization,  issuance and sale of
the Shares, and for the purposes of this opinion,  have assumed such proceedings
will be timely completed in the manner presently proposed.  In addition, we have
made such legal and factual examinations and inquires,  including an examination
of originals or copies certified or otherwise  identified to our satisfaction of
such documents,  corporate records and instruments,  as we have deemed necessary
or appropriate for purposes of this opinion.

                  In our  examination,  we have assumed the  genuineness  of all
signatures,  the authenticity of all documents submitted to us as originals, and
the conformity to authentic original documents of all documents  submitted to us
as copies.

                  We  are  opining  herein  as to  the  effect  on  the  subject
transaction  only of the internal  laws of the State of New York and the General
Corporation Law of the State of Delaware, and we express no opinion with respect
to the applicability  thereto,  or the effect thereon,  of the laws of any other
jurisdiction  or, in the case of Delaware,  any other laws, or as to any matters
of municipal law or the laws of any local agency within any state.

                                       10



 




                  Subject to the  foregoing,  it is our opinion  that the Shares
have been duly authorized and, when issued and sold upon exercise of the options
for such Shares and payment of the exercise  price therefor as  contemplated  by
the Plans will be validly issued, fully paid and nonassessable.

                  We consent to your  filing  this  opinion as an exhibit to the
Registration Statement.


                                                 Very truly yours,


                                                 /s/ LATHAM & WATKINS



                                       11