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                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549

                              AMENDMENT NO. 1 TO

                                  FORM 10-Q/A


  X            QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d)
-----               OF THE SECURITIES EXCHANGE ACT OF 1934

                 For the quarterly period ended June 30, 1999
                                      OR

           TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 (d) OF THE
                        SECURITIES EXCHANGE ACT OF 1934

             For the transition period from          to         .
                                            --------    --------
                       Commission File Number: 000-21589

                        TRIANGLE PHARMACEUTICALS, INC.
            (Exact name of Registrant as specified in its charter)

              DELAWARE                                       56-1930728
  (State or other jurisdiction                           (I.R.S. Employer
  of incorporation or organization)                      Identification No.)

         4 University Place
         4611 University Drive
         Durham, North Carolina                                27707
(Address of principal executive offices)                     (zip code)

      Registrant's telephone number, including area code: (919) 493-5980

         Indicate by check mark whether the registrant (1) has filed all
reports required to be filed by Section 13 or 15(d) of the Securities
Exchange Act of 1934 during the preceding 12 months (or for such shorter
period that the registrant was required to file such reports), and (2) has
been subject to such filing requirements for the past 90 days. Yes X  No __

         As of August 5, 1999, there were 37,523,268 shares of Triangle
Pharmaceuticals, Inc. Common Stock outstanding.

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                          PART II - OTHER INFORMATION


ITEM 6.  EXHIBITS AND REPORTS ON FORM 8-K

a.       Exhibits

                (1)3.1   Restated Certificate of Incorporation of the Company
                (1)3.2   Second Restated Certificate of Incorporation of the
                           Company

                 +10.1     Exclusive License Agreement among Glaxo Group
                           Limited, The Wellcome Foundation Limited, Glaxo
                           Wellcome Inc., Emory University and the Company dated
                           May 6, 1999

                 +10.2     Settlement Agreement by and among Emory University,
                           the Company, Dr. David W. Barry, Glaxo Wellcome plc,
                           Glaxo Wellcome Inc., Glaxo Group Limited and The
                           Wellcome Foundation Limited dated May 6, 1999

                  10.3     Amendment to License Agreement by and between Bukwang
                           Pharm. Ind. Co., Ltd., and the Company dated April 1,
                           1999

                  10.4     First Amendment to License Agreement by and between
                           the Company and Emory University dated May 6, 1999

               (2)10.5     Amendment Number One to the Agreement and Plan of
                           Merger by and among Avid Corporation, the Company and
                           Forrest H. Anthony, Alan G. Walton and Marcia T.
                           Bates dated February 28, 1999

               (2)10.6     Amendment Number One to the Agreement and Plan of
                           Reorganization by and among the Company, Avid
                           Corporation and Forrest H. Anthony, Alan G. Walton
                           and Marcia T. Bates dated February 28, 1999

               (2)11.1     Computation of Net Loss Per Common Share

               (2)27.1     Financial Data Schedule

               (2)99.1     Press release, dated August 13, 1999

                  (+) Certain confidential portions of this Exhibit were omitted
                      by means of marking such portions with an asterisk (the
                      "Mark"). This Exhibit has been filed separately with the
                      Secretary of the Commission without the Mark pursuant to
                      the Company's Application Requesting Confidential
                      Treatment under Rule 406 under the Securities Act.

                  (1) These exhibits were previously filed as part of, and are
                      hereby incorporated by reference to, the same numbered
                      exhibit filed with the Company's Form 10-K (No. 000-21589)
                      filed on March 19, 1999.

                  (2) Previously filed.

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                        TRIANGLE PHARMACEUTICALS, INC.
                                  SIGNATURES

         Pursuant to the requirements of the Securities Exchange Act of 1934,
the Registrant has duly caused this Quarterly Report on Form 10-Q to be
signed on its behalf by the undersigned, thereunto duly authorized.

                                    TRIANGLE PHARMACEUTICALS, INC.

Date: November 2, 1999              By: /s/ David W. Barry
                                    --------------------------------------------
                                    David W. Barry
                                    Chairman and Chief Executive Officer


                                    TRIANGLE PHARMACEUTICALS, INC.

Date: November 2, 1999              By: /s/ Thomas R. Staab, II
                                    --------------------------------------------
                                    Thomas R. Staab, II
                                    Acting Chief Financial Officer and Treasurer