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                                                                       EXHIBIT 5

                         STRADLING YOCCA CARLSON & RAUTH
                           A PROFESSIONAL CORPORATION
                                ATTORNEYS AT LAW
                      660 NEWPORT CENTER DRIVE, SUITE 1600
                         NEWPORT BEACH, CALIFORNIA 92660

                            TELEPHONE (949) 725-4000
                               FAX (949) 725-4100



                                  May 11, 1998

NeoTherapeutics, Inc.
157 Technology Drive
Irvine, California 92618

        Re:    Registration Statement on Form S-3

Ladies and Gentlemen:

        At your request, we have examined the form of Registration Statement on
Form S-3 (the "Registration Statement"), being filed by NeoTherapeutics, Inc., a
Delaware corporation (the "Company"), with the Securities and Exchange
Commission in connection with the registration under the Securities Act of 1933
for resale of an aggregate of up to 730,000 shares (the "Shares") of Common
Stock, par value $.001 per share, of the Company (the "Common Stock"), as
follows: (i) 700,000 shares of Common Stock (the "Equity Line Shares"), which
may be issued pursuant to a Private Equity Line of Credit Agreement dated March
27, 1998 (the "Equity Line Agreement") between the Company and one of the
selling stockholders named in the Registration Statement (the "Equity Line
Stockholder"), (ii) 5,000 shares of Common Stock, which have been issued to one
of the selling stockholders named in the Registration Statement (the "Placement
Stockholder," and together with the Equity Line Stockholder, the "Selling
Stockholders") for advisory services rendered in connection with the negotiation
of the Equity Line Agreement and (iii) 25,000 shares of Common Stock, which are
issuable upon exercise of a currently outstanding warrant (the "Warrant") issued
to the Equity Line Stockholder. The Shares may be sold from time to time for the
account of the Selling Stockholders.

        We have examined the proceedings heretofore taken and are familiar with
the additional proceedings proposed to be taken by the Company in connection
with the authorization, issuance and sale of the securities referred to above.

        Based on the foregoing, and assuming that the full consideration for
each Equity Line Share and for each share issuable upon exercise of the Warrant
is received by the Company in accordance with the terms of the Equity Line
Agreement and the Warrant, respectively, it is our opinion that the Shares
covered by the Registration Statement will be validly issued and outstanding,
fully paid and nonassessable.

        We consent to the use of this opinion as an exhibit to the Registration
Statement and to the use of our name under the caption "Legal Matters" in the
Prospectus which is part of the Registration Statement.

                                              Very truly yours,

                                              STRADLING YOCCA CARLSON & RAUTH