<PAGE>



      AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON MAY 24, 2002
                                              Registration No.   333-
================================================================================
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                        ---------------------------------
                                    FORM S-8
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

                        ---------------------------------
                          TRIANGLE PHARMACEUTICALS, INC.
                (Exact name of Registrant as Specified in Its Charter)


         Delaware                                            56-1930728
(State or Other Jurisdiction of                          (I.R.S. Employer
 Incorporation or Organization)                          Identification No.)

                                   ----------
                               4 University Place,
                             4611 University Drive,
                          Durham, North Carolina, 27707
                                 (919) 493-5980
    (Address, Including Zip Code, And Telephone Number, Including Area Code,
                  Of Registrant's Principal Executive Offices)
                                   ----------
                         Triangle Pharmaceuticals, Inc.
                            1996 Stock Incentive Plan
                            (Full Title of the Plans)
                                   ----------
                                 Chris A. Rallis
                        President and Chief Operating Officer

                         TRIANGLE PHARMACEUTICALS, INC.
                               4 University Place,
                             4611 University Drive,
                          Durham, North Carolina 27707
                                 (919) 493-5980
    (Name, Address, Including Zip Code, and Telephone Number, Including Area
                           Code, of Agent For Service)
                                   ----------

                         CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>

------------------------------------------------------------------------------------------------------------------------------
TITLE OF SECURITIES                                 PROPOSED MAXIMUM        PROPOSED MAXIMUM
       TO BE                  AMOUNT TO BE           OFFERING PRICE              AGGREGATE              AMOUNT OF
    REGISTERED               REGISTERED (1)           PER SHARE (2)          OFFERING PRICE (2)      REGISTRATION FEE
==============================================================================================================================
<S>                           <C>                    <C>                       <C>                    <C>
Common Stock, $0.001 par
  value per share             1,962,329 shares              $3.80                  $7,456,850                   $686
------------------------------------------------------------------------------------------------------------------------------
</TABLE>


(1) This Registration Statement shall also cover any additional shares of Common
Stock which become issuable under the Triangle Pharmaceuticals, Inc. 1996 Stock
Incentive Plan by reason of any stock dividend, stock split, recapitalization or
other similar transaction effected without Registrant's receipt of consideration
which results in an increase in the number of the outstanding shares of
Registrant's Common Stock.

(2) Calculated solely for purposes of this offering under Rule 457(h) of the
Securities Act of 1933, as amended, on the basis of the average of the high and
low selling prices per share of the Registrant's Common Stock on May 23, 2002,
as reported by the Nasdaq National Market.


<PAGE>





                                     PART II


               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE

         This Registration Statement on Form S-8 (the "Registration Statement")
relates to the registration of an additional 1,962,329 shares (the "Shares") of
Common Stock, $.001 par value, of the Registrant. The Shares are securities of
the same class and relating to the same employee benefit plan, the Triangle
Pharmaceuticals, Inc. 1996 Stock Incentive Plan, as those shares registered in
the Registrant's Registration Statements on Form S-8, previously filed with the
Securities and Exchange Commission on June 5, 1998 (Registration No. 333-56189),
March 22, 1999 (Registration No. 333-74805), January 14, 2000 (Registration No.
333-94725), January 31, 2001 (Registration No. 333-54696), and January 14, 2002
(Registration No. 333-76680). The earlier Registration Statements on Form S-8
are hereby incorporated by reference.

         The financial statements contained in the Registrant's Annual Report on
Form 10-K for the year ended December 31, 2001 are incorporated by reference in
this Registration Statement and have been so incorporated in reliance on the
report of PricewaterhouseCoopers LLP, independent accountants, given on the
authority of said firm as experts in auditing and accounting.

The following additional documents are incorporated by reference in this
registration statement:

         1.       Our Quarterly Report on Form 10-Q for the quarterly period
                  ended March 31, 2002 filed on May 10, 2002;

         2.       Our Annual Report on Form 10-K for the fiscal year ended
                  December 31, 2001 filed on March 25, 2002, including
                  information in our Definitive Proxy Statement in connection
                  with our 2002 Annual Meeting of Stockholders;

         3.       Our Current Report on Form 8-K filed May 2, 2002; and

         4.       The description of our common stock contained in our
                  Registration Statements on Form 8-A filed October 18, 1996,
                  February 10, 1999, June 18, 1999 and August 24, 2001.

         All documents filed by the Company pursuant to Sections 13(a), 13(c),
14 and 15(d) of the Securities and Exchange Act of 1934, as amended (the
"Exchange Act") on or after the date of this Registration Statement and prior to
the filing of a post-effective amendment which indicates that all securities
offered have been sold or which deregisters all securities then remaining unsold
shall be deemed to be incorporated by reference in this Registration Statement
and to be part hereof from the date of filing of such documents.


                                      II-1

<PAGE>

ITEM 8.           EXHIBITS


         NUMBER            EXHIBIT
         ------            -------

         5                 Opinion and consent of Smith, Anderson, Blount,
                           Dorsett, Mitchell & Jernigan, L.L.P.
         23.1              Consent of PricewaterhouseCoopers LLP, Independent
                           Accountants.
         23.2              Consent of Smith, Anderson, Blount, Dorsett, Mitchell
                           & Jernigan, L.L.P. is contained in Exhibit 5.
         24                Power of Attorney.  Reference is made to pages II-3
                           and II-4 of this Registration Statement.


                                      II-2

<PAGE>



                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, as amended,
the Registrant certifies that it has reasonable grounds to believe that it meets
all of the requirements for filing on Form S-8, and has duly caused this
Registration Statement to be signed on its behalf by the undersigned, thereunto
duly authorized, in the City of Durham, State of North Carolina on this 24th day
of May, 2002.

                                 TRIANGLE PHARMACEUTICALS, INC.

                                 BY: /S/ CHRIS A. RALLIS
                                 -----------------------------------
                                 Chris A. Rallis
                                 President and Chief Operating Officer
                                 and Director


                                POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS:

         That the undersigned officers and directors of Triangle
Pharmaceuticals, Inc., a Delaware corporation, do hereby constitute and appoint
Chris A. Rallis and Robert F. Amundsen, Jr. and each one of them, the lawful
attorneys-in-fact and agents with full power and authority to do any and all
acts and things and to execute any and all instruments which said attorneys and
agents, and any one of them, determine may be necessary or advisable or required
to enable said corporation to comply with the Securities Act of 1933, as
amended, and any rules or regulations or requirements of the Securities and
Exchange Commission in connection with this Registration Statement. Without
limiting the generality of the foregoing power and authority, the powers granted
include the power and authority to sign the names of the undersigned officers
and directors in the capacities indicated below to this Registration Statement,
to any and all amendments, both pre-effective and post-effective, and
supplements to this Registration Statement, and to any and all instruments or
documents filed as part of or in conjunction with this Registration Statement or
amendments or supplements thereof, and each of the undersigned hereby ratifies
and confirms all that said attorneys and agents, or any one of them, shall do or
cause to be done by virtue hereof. This Power of Attorney may be signed in
several counterparts.

         IN WITNESS WHEREOF, each of the undersigned has executed this Power of
Attorney as of the date indicated.

         Pursuant to the requirements of the Securities Act of 1933, as amended,
this Registration Statement has been signed below by the following persons in
the capacities and on the dates indicated.

                                      II-3


<PAGE>

<TABLE>
<CAPTION>

               SIGNATURE                                        TITLE
               ---------                                        -----


<S>                                     <C>                                                   <C>
/s/ Chris A. Rallis                       Director, President and Chief Operating
-----------------------------              Officer (Principal Executive Officer)                May 24, 2002
   Chris A. Rallis


/s/ Robert F. Amundsen, Jr.             Executive Vice President and Chief Financial
-----------------------------        Officer (Principal Financial and Accounting Officer)       May 24, 2002
   Robert F. Amundsen, Jr.

/s/ Anthony B. Evnin                                          Director                          May 24, 2002
-----------------------------
    Anthony B. Evnin

/s/ Standish M. Fleming                                       Director                          May 24, 2002
-----------------------------
    Standish M. Fleming

/s/ Dennis B. Gillings                                        Director                          May 24, 2002
-----------------------------
    Dennis B. Gillings

/s/ Henry G. Grabowski                                        Director                          May 24, 2002
-----------------------------
    Henry G. Grabowski

/s/ Stewart J. Hen                                            Director                          May 24, 2002
-----------------------------
     Stewart J. Hen

/s/ Jonathan S. Leff                                          Director                          May 24, 2002
-----------------------------
    Jonathan S. Leff

/s/ George McFadden                                           Director                          May 24, 2002
-----------------------------
      George McFadden

                                                              Director
-----------------------------
      James L. Tyree

</TABLE>


                                      II-4

<PAGE>





                                  EXHIBIT INDEX

         NUMBER           EXHIBIT
         ------           -------

         5                 Opinion and consent of Smith, Anderson, Blount,
                           Dorsett, Mitchell & Jernigan, L.L.P.
         23.1              Consent of PricewaterhouseCoopers LLP, Independent
                           Accountants.
         23.2              Consent of Smith, Anderson, Blount, Dorsett, Mitchell
                           & Jernigan, L.L.P. is contained in Exhibit 5.
         24                Power of Attorney.  Reference is made to pages II-3
                           and II-4 of this Registration Statement.
[{"type": "S-8", "sequence": "1", "filename": "a2081047zs-8.txt", "description": "S-8", "secsgml_size_bytes": 12850}]
{"company-data": {"conformed-name": "TRIANGLE PHARMACEUTICALS INC", "cik": "0001022622", "assigned-sic": "2834", "irs-number": "561930728", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-89084", "film-number": "02662328"}, "business-address": {"street1": "4611 UNIVERSITY DRIVE", "city": "DURHAM", "state": "NC", "zip": "27707", "phone": "9194935980"}, "mail-address": {"street1": "4611 UNIVERSITY DRIVE", "city": "DURHAM", "state": "NC", "zip": "27707"}}
AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON MAY 24, 2002
                                              Registration No.   333-
================================================================================
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                        ---------------------------------
                                    FORM S-8
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

                        ---------------------------------
                          TRIANGLE PHARMACEUTICALS, INC.
                (Exact name of Registrant as Specified in Its Charter)

         Delaware                                            56-1930728
(State or Other Jurisdiction of                          (I.R.S. Employer
 Incorporation or Organization)                          Identification No.)

                                   ----------
                               4 University Place,
                             4611 University Drive,
                          Durham, North Carolina, 27707
                                 (919) 493-5980
    (Address, Including Zip Code, And Telephone Number, Including Area Code,
                  Of Registrant's Principal Executive Offices)
                                   ----------
                         Triangle Pharmaceuticals, Inc.
                            1996 Stock Incentive Plan
                            (Full Title of the Plans)
                                   ----------
                                 Chris A. Rallis
                        President and Chief Operating Officer

                         TRIANGLE PHARMACEUTICALS, INC.
                               4 University Place,
                             4611 University Drive,
                          Durham, North Carolina 27707
                                 (919) 493-5980
    (Name, Address, Including Zip Code, and Telephone Number, Including Area
                           Code, of Agent For Service)
                                   ----------

                         CALCULATION OF REGISTRATION FEE
------------------------------------------------------------------------------------------------------------------------------
TITLE OF SECURITIES                                 PROPOSED MAXIMUM        PROPOSED MAXIMUM
       TO BE                  AMOUNT TO BE           OFFERING PRICE              AGGREGATE              AMOUNT OF
    REGISTERED               REGISTERED (1)           PER SHARE (2)          OFFERING PRICE (2)      REGISTRATION FEE
==============================================================================================================================
Common Stock, $0.001 par
  value per share             1,962,329 shares              $3.80                  $7,456,850                   $686
------------------------------------------------------------------------------------------------------------------------------
(1) This Registration Statement shall also cover any additional shares of Common
Stock which become issuable under the Triangle Pharmaceuticals, Inc. 1996 Stock
Incentive Plan by reason of any stock dividend, stock split, recapitalization or
other similar transaction effected without Registrant's receipt of consideration
which results in an increase in the number of the outstanding shares of
Registrant's Common Stock.

(2) Calculated solely for purposes of this offering under Rule 457(h) of the
Securities Act of 1933, as amended, on the basis of the average of the high and
low selling prices per share of the Registrant's Common Stock on May 23, 2002,
as reported by the Nasdaq National Market.
PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE

         This Registration Statement on Form S-8 (the "Registration Statement")
relates to the registration of an additional 1,962,329 shares (the "Shares") of
Common Stock, $.001 par value, of the Registrant. The Shares are securities of
the same class and relating to the same employee benefit plan, the Triangle
Pharmaceuticals, Inc. 1996 Stock Incentive Plan, as those shares registered in
the Registrant's Registration Statements on Form S-8, previously filed with the
Securities and Exchange Commission on June 5, 1998 (Registration No. 333-56189),
March 22, 1999 (Registration No. 333-74805), January 14, 2000 (Registration No.
333-94725), January 31, 2001 (Registration No. 333-54696), and January 14, 2002
(Registration No. 333-76680). The earlier Registration Statements on Form S-8
are hereby incorporated by reference.

         The financial statements contained in the Registrant's Annual Report on
Form 10-K for the year ended December 31, 2001 are incorporated by reference in
this Registration Statement and have been so incorporated in reliance on the
report of PricewaterhouseCoopers LLP, independent accountants, given on the
authority of said firm as experts in auditing and accounting.

The following additional documents are incorporated by reference in this
registration statement:

         1.       Our Quarterly Report on Form 10-Q for the quarterly period
                  ended March 31, 2002 filed on May 10, 2002;

         2.       Our Annual Report on Form 10-K for the fiscal year ended
                  December 31, 2001 filed on March 25, 2002, including
                  information in our Definitive Proxy Statement in connection
                  with our 2002 Annual Meeting of Stockholders;

         3.       Our Current Report on Form 8-K filed May 2, 2002; and

         4.       The description of our common stock contained in our
                  Registration Statements on Form 8-A filed October 18, 1996,
                  February 10, 1999, June 18, 1999 and August 24, 2001.

         All documents filed by the Company pursuant to Sections 13(a), 13(c),
14 and 15(d) of the Securities and Exchange Act of 1934, as amended (the
"Exchange Act") on or after the date of this Registration Statement and prior to
the filing of a post-effective amendment which indicates that all securities
offered have been sold or which deregisters all securities then remaining unsold
shall be deemed to be incorporated by reference in this Registration Statement
and to be part hereof from the date of filing of such documents.

                                      II-1
ITEM 8.           EXHIBITS

         NUMBER            EXHIBIT
         ------            -------

         5                 Opinion and consent of Smith, Anderson, Blount,
                           Dorsett, Mitchell & Jernigan, L.L.P.
         23.1              Consent of PricewaterhouseCoopers LLP, Independent
                           Accountants.
         23.2              Consent of Smith, Anderson, Blount, Dorsett, Mitchell
                           & Jernigan, L.L.P. is contained in Exhibit 5.
         24                Power of Attorney.  Reference is made to pages II-3
                           and II-4 of this Registration Statement.

                                      II-2
SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, as amended,
the Registrant certifies that it has reasonable grounds to believe that it meets
all of the requirements for filing on Form S-8, and has duly caused this
Registration Statement to be signed on its behalf by the undersigned, thereunto
duly authorized, in the City of Durham, State of North Carolina on this 24th day
of May, 2002.

                                 TRIANGLE PHARMACEUTICALS, INC.

                                 BY: /S/ CHRIS A. RALLIS
                                 -----------------------------------
                                 Chris A. Rallis
                                 President and Chief Operating Officer
                                 and Director

                                POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS:

         That the undersigned officers and directors of Triangle
Pharmaceuticals, Inc., a Delaware corporation, do hereby constitute and appoint
Chris A. Rallis and Robert F. Amundsen, Jr. and each one of them, the lawful
attorneys-in-fact and agents with full power and authority to do any and all
acts and things and to execute any and all instruments which said attorneys and
agents, and any one of them, determine may be necessary or advisable or required
to enable said corporation to comply with the Securities Act of 1933, as
amended, and any rules or regulations or requirements of the Securities and
Exchange Commission in connection with this Registration Statement. Without
limiting the generality of the foregoing power and authority, the powers granted
include the power and authority to sign the names of the undersigned officers
and directors in the capacities indicated below to this Registration Statement,
to any and all amendments, both pre-effective and post-effective, and
supplements to this Registration Statement, and to any and all instruments or
documents filed as part of or in conjunction with this Registration Statement or
amendments or supplements thereof, and each of the undersigned hereby ratifies
and confirms all that said attorneys and agents, or any one of them, shall do or
cause to be done by virtue hereof. This Power of Attorney may be signed in
several counterparts.

         IN WITNESS WHEREOF, each of the undersigned has executed this Power of
Attorney as of the date indicated.

         Pursuant to the requirements of the Securities Act of 1933, as amended,
this Registration Statement has been signed below by the following persons in
the capacities and on the dates indicated.

                                      II-3
SIGNATURE                                        TITLE
               ---------                                        -----
/s/ Chris A. Rallis                       Director, President and Chief Operating
-----------------------------              Officer (Principal Executive Officer)                May 24, 2002
   Chris A. Rallis

/s/ Robert F. Amundsen, Jr.             Executive Vice President and Chief Financial
-----------------------------        Officer (Principal Financial and Accounting Officer)       May 24, 2002
   Robert F. Amundsen, Jr.

/s/ Anthony B. Evnin                                          Director                          May 24, 2002
-----------------------------
    Anthony B. Evnin

/s/ Standish M. Fleming                                       Director                          May 24, 2002
-----------------------------
    Standish M. Fleming

/s/ Dennis B. Gillings                                        Director                          May 24, 2002
-----------------------------
    Dennis B. Gillings

/s/ Henry G. Grabowski                                        Director                          May 24, 2002
-----------------------------
    Henry G. Grabowski

/s/ Stewart J. Hen                                            Director                          May 24, 2002
-----------------------------
     Stewart J. Hen

/s/ Jonathan S. Leff                                          Director                          May 24, 2002
-----------------------------
    Jonathan S. Leff

/s/ George McFadden                                           Director                          May 24, 2002
-----------------------------
      George McFadden

                                                              Director
-----------------------------
      James L. Tyree
II-4
EXHIBIT INDEX

         NUMBER           EXHIBIT
         ------           -------

         5                 Opinion and consent of Smith, Anderson, Blount,
                           Dorsett, Mitchell & Jernigan, L.L.P.
         23.1              Consent of PricewaterhouseCoopers LLP, Independent
                           Accountants.
         23.2              Consent of Smith, Anderson, Blount, Dorsett, Mitchell
                           & Jernigan, L.L.P. is contained in Exhibit 5.
         24                Power of Attorney.  Reference is made to pages II-3
                           and II-4 of this Registration Statement.