<PAGE>   1
   As filed with the Securities and Exchange Commission on September 3, 1998
                                                           Registration No. 333-
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                   ----------

                                    FORM S-8
                             REGISTRATION STATEMENTS
                                      Under
                           The Securities Act of 1933

                                   ----------

                        IDEC PHARMACEUTICALS CORPORATION
             (Exact name of registrant as specified in its charter)

                 DELAWARE                               33-0112644
       (State or other jurisdiction         (IRS Employer Identification No.)
     of incorporation or organization)

                              11011 TORREYANA ROAD
                           SAN DIEGO, CALIFORNIA 92121
               (Address of principal executive offices) (Zip Code)

                                   ----------

                   AMENDED AND RESTATED 1988 STOCK OPTION PLAN
                  1993 NON-EMPLOYEE DIRECTORS STOCK OPTION PLAN
                           (Full titles of the Plans)

                                   ----------

                           WILLIAM H. RASTETTER, PH.D.
                 CHAIRMAN, PRESIDENT AND CHIEF EXECUTIVE OFFICER
                        IDEC PHARMACEUTICALS CORPORATION
                    11011 TORREYANA ROAD, SAN DIEGO, CA 92121
                     (Name and address of agent for service)
                                 (619) 550-8500
          (Telephone number, including area code, of agent for service)

                                   ----------

                         CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
                                                                  Proposed             Proposed
                                                                   Maximum              Maximum
                                         Amount to be           Offering Price     Aggregate Offering       Amount of
Title of Securities to be Registered    Registered(1)            per Share(2)           Price(2)          Registration Fee
===================================================================================================================================
<S>                                     <C>                     <C>                <C>                   <C>
Amended and Restated 1988 Stock
Option Plan

Common Stock, $0.001 par value          855,000 shares          $        19.50       $   16,672,500       $     4,918.39
                                                                --------------       --------------       --------------

1993 Non-Employee Directors
Stock Option Plan

Common Stock, $0.001 par value          120,000 shares          $        19.50       $    2,340,000       $       630.30
                                                                --------------       --------------       --------------

                                                                                   Aggregate Filing Fee:  $     5,548.69
                                                                                                          --------------

===================================================================================================================================
</TABLE>

(1)     This Registration Statement shall also cover any additional shares of
        Common Stock which become issuable under the Amended and Restated 1988
        Stock Option Plan and/or the 1993 Non-Employee Director Stock Option
        Plan by reason of any stock dividend, stock split, recapitalization or
        other similar transaction effected without the 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, (the "1933 Act") on the basis of the
        average of the high and low selling prices per share of Registrant's
        Common Stock on August 31, 1998 as reported by the Nasdaq National
        Market.



<PAGE>   2

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT


ITEM 3. INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

     IDEC Pharmaceuticals Corporation (the "Registrant") hereby incorporates by
reference into this Registration Statement the following documents previously
filed with the Securities and Exchange Commission (the "Commission"):

     (a)  The Registrant's Annual Report on Form 10-K for the fiscal year ended
          December 31, 1997 filed with the Commission on February 27, 1998, as
          amended on Form 10-K/A filed with the Commission on March 3, 1998,
          pursuant to Section 13 of the Securities Exchange Act of 1934, as
          amended (the "Exchange Act");

     (b)  The Registrant's Quarterly Report on Form 10-Q for the fiscal quarter
          ended June 30, 1998 filed with the Commission on August 14, 1998
          pursuant to Section 13 of the Exchange Act;

     (c)  The Registrant's Quarterly Report on Form 10-Q for the fiscal quarter
          ended March 31, 1998 filed with the Commission on May 15, 1998
          pursuant to Section 13 of the Exchange Act; and

     (d)  The Registrant's Registration Statement No. 0-19311 on Form 8-B filed
          with the Commission on June 2, 1997, in which there is described the
          terms, rights and provisions applicable to the Registrant's
          outstanding Common Stock.

     All reports and definitive proxy or information statements filed pursuant
to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of this
Registration Statement and prior to the filing of a post-effective amendment
which indicates that all securities offered hereby have been sold or which
deregisters all securities then remaining unsold shall be deemed to be
incorporated by reference into this Registration Statement and to be a part
hereof from the date of filing of such documents. Any statement contained in a
document incorporated or deemed to be incorporated by reference herein shall be
deemed to be modified or superseded for purposes of this Registration Statement
to the extent that a statement contained herein or in any subsequently filed
document which is also deemed to be incorporated by reference herein modifies or
supersedes such statement. Any such statement so modified or superseded shall
not be deemed, except as so modified or superseded, to constitute a part of this
Registration Statement.


ITEM 4. DESCRIPTION OF SECURITIES

     Not applicable.


ITEM 5. INTERESTS OF NAMED EXPERTS AND COUNSEL

     Not applicable.



<PAGE>   3

ITEM 6. INDEMNIFICATION OF DIRECTORS AND OFFICERS

     The Registrant's Certificate of Incorporation limits the liability of
directors to the maximum extent permitted by Delaware law. Delaware law provides
that directors of a corporation will not be personally liable for monetary
damages for breach of their fiduciary duties as directors, except for liability
for (i) any breach of their duty of loyalty to the corporation or its
stockholders, (ii) acts or omissions not in good faith or which involve
intentional misconduct or a knowing violation of law, (iii) unlawful payments of
dividends or unlawful stock repurchases or redemptions as provided in Section
174 of the Delaware General Corporation Law or (iv) any transaction from which
the director derived an improper personal benefit.

     The Registrant's Bylaws provide that the Registrant shall indemnify its
directors and may indemnify its officers and employees and other agents to the
fullest extent permitted by law. The Registrant believes that indemnification
under its Bylaws covers at least negligence and gross negligence on the part of
indemnified parties. The Registrant's Bylaws also permit it to secure insurance
on behalf of any officer, director, employee or other agent for any liability
arising out of his or her actions in such capacity, regardless of whether the
Bylaws have the power to indemnify him or her against such liability under the
General Corporation Law of Delaware. The Registrant currently has secured such
insurance on behalf of its directors and officers.

     The Registrant has entered into agreements to indemnify its directors and
executive officers, in addition to indemnification provided for in the
Registrant's Bylaws. These agreements, among other things, indemnify the
Registrant's directors and executive officers for certain expenses (including
attorneys' fees), judgments, fines and settlement amounts incurred by any such
person in any action or proceeding, including any action by or in the right of
the Registrant, arising out of such person's services as a director or executive
officer of the Registrant, any subsidiary of the Registrant or any other company
or enterprise to which the person provides services at the request of the
Registrant. The Registrant believes that these provisions and agreements are
necessary to attract and retain qualified persons as directors and executive
officers.

ITEM 7. EXEMPTION FROM REGISTRATION CLAIMED

     Not applicable.

ITEM 8. EXHIBITS

<TABLE>
<CAPTION>
   Exhibit Number         Exhibit
   --------------         -------
<S>                       <C>
     4                    Instruments Defining Rights of Stockholders.  Reference is made to Registrant's Registration
                          Statement No. 0-19311 on Form 8-B, including exhibits thereto, which is incorporated herein
                          by reference pursuant to Item 3(c).
     5.1                  Opinion of Brobeck, Phleger & Harrison LLP.
     23.1                 Consent of Independent Auditors - KPMG Peat Marwick LLP.
     23.2                 Consent of Brobeck, Phleger & Harrison LLP is contained in Exhibit 5.1.
     24                   Power of Attorney.  Reference is made to page II-4 of this Registration Statement.
     99.1                 Amended and Restated 1988 Stock Option Plan (Amended and Restated February 20, 1998).
     99.2*                Form of Notice of Grant.
     99.3*                Form of Stock Option Agreement.
     99.4                 1993 Non-Employee Directors Stock Option Plan (Amended and Restated February 20, 1998).
     99.5**               Form of Notice of Grant of Automatic Stock Option (New Director).
     99.6**               Form of Notice of Grant of Automatic Stock Option (Continuing Director).
     99.7**               Form of Stock Option Agreement.
</TABLE>



                                      II-2
<PAGE>   4

*    Exhibits 99.22 and 99.3 are incorporated herein by reference to Exhibits
     28.2 and 28.3, respectively, of Registrant's Registration Statement No.
     33-45172 on Form S-8 which was filed with the Commission on January 21,
     1992.

**   Exhibits 99.5, 99.6 and 99.7 are incorporated herein by reference to
     Exhibits 99.2, 99.3 and 99.4, respectively, of Registrant's Registration
     Statement No. 33-93794 on Form S-8 which was filed with the Commission on
     June 25, 1995.


ITEM 9. UNDERTAKINGS

     A. The undersigned Registrant hereby undertakes: (1) to file, during any
period in which offers or sales are being made, a post-effective amendment to
this Registration Statement (i) to include any prospectus required by Section
10(a)(3) of the 1933 Act, (ii) to reflect in the prospectus any facts or events
arising after the effective date of this Registration Statement (or the most
recent post-effective amendment thereof) which, individually or in the
aggregate, represent a fundamental change in the information set forth in this
Registration Statement, and (iii) to include any material information with
respect to the plan of distribution not previously disclosed in this
Registration Statement or any material change to such information in this
Registration Statement; provided, however, that clauses (1)(i) and (1)(ii) shall
not apply if the information required to be included in a post-effective
amendment by those paragraphs is contained in periodic reports filed by the
Registrant pursuant to Section 13 or Section 15(d) of the Exchange Act that are
incorporated by reference into this Registration Statement; (2) that for the
purpose of determining any liability under the 1933 Act, each such
post-effective amendment shall be deemed to be a new registration statement
relating to the securities offered therein and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof; and
(3) to remove from registration by means of a post-effective amendment any of
the securities being registered which remain unsold at the termination of the
Registrant's Amended and Restated 1988 Stock Option Plan and/or 1993
Non-Employee Directors Stock Option Plan.

     B. The undersigned Registrant hereby undertakes that, for purposes of
determining any liability under the 1933 Act, each filing of the Registrant's
annual report pursuant to Section 13(a) or Section 15(d) of the Exchange Act
that is incorporated by reference into this Registration Statement shall be
deemed to be a new registration statement relating to the securities offered
therein, and the offering of such securities at that time shall be deemed to be
the initial bona fide offering thereof.

     C. Insofar as indemnification for liabilities arising under the 1933 Act
may be permitted to directors, officers or controlling persons of the Registrant
pursuant to the indemnity provisions summarized in Item 6 or otherwise, the
Registrant has been informed that in the opinion of the Securities and Exchange
Commission such indemnification is against public policy as expressed in the
1933 Act and is, therefore, unenforceable. In the event that a claim for
indemnification against such liabilities (other than the payment by the
Registrant of expenses incurred or paid by a director, officer or controlling
person of the Registrant in the successful defense of any action, suit or
proceeding) is asserted by such director, officer or controlling person in
connection with the securities being registered, the Registrant will, unless in
the opinion of its counsel the matter has been settled by controlling precedent,
submit to a court of appropriate jurisdiction the question whether such
indemnification by it is against public policy as expressed in the 1933 Act and
will be governed by the final adjudication of such issue.



                                      II-3
<PAGE>   5

                                   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 San Diego, State of California, on this 31st day of
August, 1998.

                                            IDEC PHARMACEUTICALS CORPORATION


                                            By /s/WILLIAM H. RASTETTER, PH.D.
                                               ---------------------------------
                                               William H. Rastetter, Ph.D.
                                               Chairman, President and Chief 
                                               Executive Officer

                                POWER OF ATTORNEY

KNOW ALL MEN BY THESE PRESENTS:

     That the undersigned officers and directors of IDEC Pharmaceuticals
Corporation, a Delaware corporation, do hereby constitute and appoint William H.
Rastetter and Phillip M. Schneider, and each of them, the lawful attorneys 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, determines 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, and 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.

<TABLE>
<CAPTION>
Signatures                                  Title                                             Date
----------                                  -----                                             ----

<S>                                         <C>                                               <C>
/s/WILLIAM H. RASTETTER, PH.D.              Chairman, President and                           August 31, 1998
------------------------------              Chief Executive Officer                                 
William H. Rastetter, Ph.D.                 (Principal Executive Officer)
                                            


/S/PHILLIP M. SCHNEIDER                     Vice President and Chief                          August 31, 1998
--------------------------------------      Financial Officer (Principal                            
Phillip M. Schneider                        Financial and Accounting Officer)
                                            
</TABLE>



                                      II-4
<PAGE>   6

<TABLE>
<CAPTION>
Signatures                                  Title                                             Date
----------                                  -----                                             ----

<S>                                         <C>                                               <C>
/S/CHARLES C. EDWARDS, M.D.                 Director                                          August 31, 1998
--------------------------------------                                                              
Charles C. Edwards, M.D.



/S/ALAN B. GLASSBERG, M.D.                  Director                                          August 31, 1998
--------------------------------------                                                              
Alan B. Glassberg, M.D.



                                            Director                                          August   , 1998
--------------------------------------                                                              ----
John Groom



                                            Director                                          August   , 1998
--------------------------------------                                                              ----
Kazuhiro Hashimoto



/S/FRANKLIN P. JOHNSON, JR.                 Director                                          August 31, 1998
--------------------------------------                                                              
Franklin P. Johnson, Jr.



/S/LYNN SCHENK                              Director                                          August 31, 1998
--------------------------------------                                                             
Lynn Schenk



/S/WILLIAM D. YOUNG                         Director                                          August 31, 1998
--------------------------------------                                                              
William D. Young



/S/ROBERT W. PANGIA                         Director                                          August 31, 1998
--------------------------------------                                                              
Robert W. Pangia



/S/BRUCE R. ROSS                            Director                                          August 31, 1998
--------------------------------------                                                              
Bruce R. Ross
</TABLE>



                                      II-5
<PAGE>   7

                                  EXHIBIT INDEX


<TABLE>
<CAPTION>
   Exhibit Number         Exhibit
   --------------         -------
<S>                       <C>
     4                    Instruments Defining Rights of Stockholders.  Reference is made to Registrant's Registration
                          Statement No. 0-19311 on Form 8-B, including exhibits thereto, which is incorporated herein
                          by reference pursuant to Item 3(c).
     5.1                  Opinion of Brobeck, Phleger & Harrison LLP.
     23.1                 Consent of Independent Auditors - KPMG Peat Marwick LLP.
     23.2                 Consent of Brobeck, Phleger & Harrison LLP is contained in Exhibit 5.1.
     24                   Power of Attorney.  Reference is made to page II-4 of this Registration Statement.
     99.1                 Amended and Restated 1988 Stock Option Plan (Amended and Restated February 20, 1998).
     99.2*                Form of Notice of Grant.
     99.3*                Form of Stock Option Agreement.
     99.4                 1993 Non-Employee Directors Stock Option Plan (Amended and Restated February 20, 1998).
     99.5**               Form of Notice of Grant of Automatic Stock Option (New Director).
     99.6**               Form of Notice of Grant of Automatic Stock Option (Continuing Director).
     99.7**               Form of Stock Option Agreement.
</TABLE>

*    Exhibits 99.2 and 99.3 are incorporated herein by reference to Exhibits
     28.2 and 28.3, respectively, of Registrant's Registration Statement No.
     33-45172 on Form S-8 which was filed with the Commission on January 21,
     1992.

**   Exhibits 99.5, 99.6 and 99.7 are incorporated herein by reference to
     Exhibits 99.2, 99.3 and 99.4, respectively, of Registrant's Registration
     Statement No. 33-93794 on Form S-8 which was filed with the Commission on
     June 25, 1995.
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 23089}]
{"company-data": {"conformed-name": "IDEC PHARMACEUTICALS CORP / DE", "cik": "0000875045", "assigned-sic": "2836", "irs-number": "330112644", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-62817", "film-number": "98703717"}, "business-address": {"street1": "11011 TORREYANA ROAD", "city": "SAN DIEGO", "state": "CA", "zip": "92121", "phone": "6195508500"}, "mail-address": {"street1": "11011 TORREYANA ROAD", "city": "SAN DIEGO", "state": "CA", "zip": "92121"}}
1
   As filed with the Securities and Exchange Commission on September 3, 1998
                                                           Registration No. 333-
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                   ----------

                                    FORM S-8
                             REGISTRATION STATEMENTS
                                      Under
                           The Securities Act of 1933

                                   ----------

                        IDEC PHARMACEUTICALS CORPORATION
             (Exact name of registrant as specified in its charter)

                 DELAWARE                               33-0112644
       (State or other jurisdiction         (IRS Employer Identification No.)
     of incorporation or organization)

                              11011 TORREYANA ROAD
                           SAN DIEGO, CALIFORNIA 92121
               (Address of principal executive offices) (Zip Code)

                                   ----------

                   AMENDED AND RESTATED 1988 STOCK OPTION PLAN
                  1993 NON-EMPLOYEE DIRECTORS STOCK OPTION PLAN
                           (Full titles of the Plans)

                                   ----------

                           WILLIAM H. RASTETTER, PH.D.
                 CHAIRMAN, PRESIDENT AND CHIEF EXECUTIVE OFFICER
                        IDEC PHARMACEUTICALS CORPORATION
                    11011 TORREYANA ROAD, SAN DIEGO, CA 92121
                     (Name and address of agent for service)
                                 (619) 550-8500
          (Telephone number, including area code, of agent for service)

                                   ----------

                         CALCULATION OF REGISTRATION FEE
Proposed             Proposed
                                                                   Maximum              Maximum
                                         Amount to be           Offering Price     Aggregate Offering       Amount of
Title of Securities to be Registered    Registered(1)            per Share(2)           Price(2)          Registration Fee
===================================================================================================================================
Amended and Restated 1988 Stock
Option Plan

Common Stock, $0.001 par value          855,000 shares          $        19.50       $   16,672,500       $     4,918.39
                                                                --------------       --------------       --------------

1993 Non-Employee Directors
Stock Option Plan

Common Stock, $0.001 par value          120,000 shares          $        19.50       $    2,340,000       $       630.30
                                                                --------------       --------------       --------------

                                                                                   Aggregate Filing Fee:  $     5,548.69
                                                                                                          --------------

===================================================================================================================================
(1)     This Registration Statement shall also cover any additional shares of
        Common Stock which become issuable under the Amended and Restated 1988
        Stock Option Plan and/or the 1993 Non-Employee Director Stock Option
        Plan by reason of any stock dividend, stock split, recapitalization or
        other similar transaction effected without the 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, (the "1933 Act") on the basis of the
        average of the high and low selling prices per share of Registrant's
        Common Stock on August 31, 1998 as reported by the Nasdaq National
        Market.
2

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3. INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

     IDEC Pharmaceuticals Corporation (the "Registrant") hereby incorporates by
reference into this Registration Statement the following documents previously
filed with the Securities and Exchange Commission (the "Commission"):

     (a)  The Registrant's Annual Report on Form 10-K for the fiscal year ended
          December 31, 1997 filed with the Commission on February 27, 1998, as
          amended on Form 10-K/A filed with the Commission on March 3, 1998,
          pursuant to Section 13 of the Securities Exchange Act of 1934, as
          amended (the "Exchange Act");

     (b)  The Registrant's Quarterly Report on Form 10-Q for the fiscal quarter
          ended June 30, 1998 filed with the Commission on August 14, 1998
          pursuant to Section 13 of the Exchange Act;

     (c)  The Registrant's Quarterly Report on Form 10-Q for the fiscal quarter
          ended March 31, 1998 filed with the Commission on May 15, 1998
          pursuant to Section 13 of the Exchange Act; and

     (d)  The Registrant's Registration Statement No. 0-19311 on Form 8-B filed
          with the Commission on June 2, 1997, in which there is described the
          terms, rights and provisions applicable to the Registrant's
          outstanding Common Stock.

     All reports and definitive proxy or information statements filed pursuant
to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of this
Registration Statement and prior to the filing of a post-effective amendment
which indicates that all securities offered hereby have been sold or which
deregisters all securities then remaining unsold shall be deemed to be
incorporated by reference into this Registration Statement and to be a part
hereof from the date of filing of such documents. Any statement contained in a
document incorporated or deemed to be incorporated by reference herein shall be
deemed to be modified or superseded for purposes of this Registration Statement
to the extent that a statement contained herein or in any subsequently filed
document which is also deemed to be incorporated by reference herein modifies or
supersedes such statement. Any such statement so modified or superseded shall
not be deemed, except as so modified or superseded, to constitute a part of this
Registration Statement.

ITEM 4. DESCRIPTION OF SECURITIES

     Not applicable.

ITEM 5. INTERESTS OF NAMED EXPERTS AND COUNSEL

     Not applicable.
3

ITEM 6. INDEMNIFICATION OF DIRECTORS AND OFFICERS

     The Registrant's Certificate of Incorporation limits the liability of
directors to the maximum extent permitted by Delaware law. Delaware law provides
that directors of a corporation will not be personally liable for monetary
damages for breach of their fiduciary duties as directors, except for liability
for (i) any breach of their duty of loyalty to the corporation or its
stockholders, (ii) acts or omissions not in good faith or which involve
intentional misconduct or a knowing violation of law, (iii) unlawful payments of
dividends or unlawful stock repurchases or redemptions as provided in Section
174 of the Delaware General Corporation Law or (iv) any transaction from which
the director derived an improper personal benefit.

     The Registrant's Bylaws provide that the Registrant shall indemnify its
directors and may indemnify its officers and employees and other agents to the
fullest extent permitted by law. The Registrant believes that indemnification
under its Bylaws covers at least negligence and gross negligence on the part of
indemnified parties. The Registrant's Bylaws also permit it to secure insurance
on behalf of any officer, director, employee or other agent for any liability
arising out of his or her actions in such capacity, regardless of whether the
Bylaws have the power to indemnify him or her against such liability under the
General Corporation Law of Delaware. The Registrant currently has secured such
insurance on behalf of its directors and officers.

     The Registrant has entered into agreements to indemnify its directors and
executive officers, in addition to indemnification provided for in the
Registrant's Bylaws. These agreements, among other things, indemnify the
Registrant's directors and executive officers for certain expenses (including
attorneys' fees), judgments, fines and settlement amounts incurred by any such
person in any action or proceeding, including any action by or in the right of
the Registrant, arising out of such person's services as a director or executive
officer of the Registrant, any subsidiary of the Registrant or any other company
or enterprise to which the person provides services at the request of the
Registrant. The Registrant believes that these provisions and agreements are
necessary to attract and retain qualified persons as directors and executive
officers.

ITEM 7. EXEMPTION FROM REGISTRATION CLAIMED

     Not applicable.

ITEM 8. EXHIBITS
Exhibit Number         Exhibit
   --------------         -------
4                    Instruments Defining Rights of Stockholders.  Reference is made to Registrant's Registration
                          Statement No. 0-19311 on Form 8-B, including exhibits thereto, which is incorporated herein
                          by reference pursuant to Item 3(c).
     5.1                  Opinion of Brobeck, Phleger & Harrison LLP.
     23.1                 Consent of Independent Auditors - KPMG Peat Marwick LLP.
     23.2                 Consent of Brobeck, Phleger & Harrison LLP is contained in Exhibit 5.1.
     24                   Power of Attorney.  Reference is made to page II-4 of this Registration Statement.
     99.1                 Amended and Restated 1988 Stock Option Plan (Amended and Restated February 20, 1998).
     99.2*                Form of Notice of Grant.
     99.3*                Form of Stock Option Agreement.
     99.4                 1993 Non-Employee Directors Stock Option Plan (Amended and Restated February 20, 1998).
     99.5**               Form of Notice of Grant of Automatic Stock Option (New Director).
     99.6**               Form of Notice of Grant of Automatic Stock Option (Continuing Director).
     99.7**               Form of Stock Option Agreement.
II-2
4

*    Exhibits 99.22 and 99.3 are incorporated herein by reference to Exhibits
     28.2 and 28.3, respectively, of Registrant's Registration Statement No.
     33-45172 on Form S-8 which was filed with the Commission on January 21,
     1992.

**   Exhibits 99.5, 99.6 and 99.7 are incorporated herein by reference to
     Exhibits 99.2, 99.3 and 99.4, respectively, of Registrant's Registration
     Statement No. 33-93794 on Form S-8 which was filed with the Commission on
     June 25, 1995.

ITEM 9. UNDERTAKINGS

     A. The undersigned Registrant hereby undertakes: (1) to file, during any
period in which offers or sales are being made, a post-effective amendment to
this Registration Statement (i) to include any prospectus required by Section
10(a)(3) of the 1933 Act, (ii) to reflect in the prospectus any facts or events
arising after the effective date of this Registration Statement (or the most
recent post-effective amendment thereof) which, individually or in the
aggregate, represent a fundamental change in the information set forth in this
Registration Statement, and (iii) to include any material information with
respect to the plan of distribution not previously disclosed in this
Registration Statement or any material change to such information in this
Registration Statement; provided, however, that clauses (1)(i) and (1)(ii) shall
not apply if the information required to be included in a post-effective
amendment by those paragraphs is contained in periodic reports filed by the
Registrant pursuant to Section 13 or Section 15(d) of the Exchange Act that are
incorporated by reference into this Registration Statement; (2) that for the
purpose of determining any liability under the 1933 Act, each such
post-effective amendment shall be deemed to be a new registration statement
relating to the securities offered therein and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof; and
(3) to remove from registration by means of a post-effective amendment any of
the securities being registered which remain unsold at the termination of the
Registrant's Amended and Restated 1988 Stock Option Plan and/or 1993
Non-Employee Directors Stock Option Plan.

     B. The undersigned Registrant hereby undertakes that, for purposes of
determining any liability under the 1933 Act, each filing of the Registrant's
annual report pursuant to Section 13(a) or Section 15(d) of the Exchange Act
that is incorporated by reference into this Registration Statement shall be
deemed to be a new registration statement relating to the securities offered
therein, and the offering of such securities at that time shall be deemed to be
the initial bona fide offering thereof.

     C. Insofar as indemnification for liabilities arising under the 1933 Act
may be permitted to directors, officers or controlling persons of the Registrant
pursuant to the indemnity provisions summarized in Item 6 or otherwise, the
Registrant has been informed that in the opinion of the Securities and Exchange
Commission such indemnification is against public policy as expressed in the
1933 Act and is, therefore, unenforceable. In the event that a claim for
indemnification against such liabilities (other than the payment by the
Registrant of expenses incurred or paid by a director, officer or controlling
person of the Registrant in the successful defense of any action, suit or
proceeding) is asserted by such director, officer or controlling person in
connection with the securities being registered, the Registrant will, unless in
the opinion of its counsel the matter has been settled by controlling precedent,
submit to a court of appropriate jurisdiction the question whether such
indemnification by it is against public policy as expressed in the 1933 Act and
will be governed by the final adjudication of such issue.

                                      II-3
5

                                   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 San Diego, State of California, on this 31st day of
August, 1998.

                                            IDEC PHARMACEUTICALS CORPORATION

                                            By /s/WILLIAM H. RASTETTER, PH.D.
                                               ---------------------------------
                                               William H. Rastetter, Ph.D.
                                               Chairman, President and Chief 
                                               Executive Officer

                                POWER OF ATTORNEY

KNOW ALL MEN BY THESE PRESENTS:

     That the undersigned officers and directors of IDEC Pharmaceuticals
Corporation, a Delaware corporation, do hereby constitute and appoint William H.
Rastetter and Phillip M. Schneider, and each of them, the lawful attorneys 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, determines 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, and 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.
Signatures                                  Title                                             Date
----------                                  -----                                             ----
/s/WILLIAM H. RASTETTER, PH.D.              Chairman, President and                           August 31, 1998
------------------------------              Chief Executive Officer                                 
William H. Rastetter, Ph.D.                 (Principal Executive Officer)
                                            

/S/PHILLIP M. SCHNEIDER                     Vice President and Chief                          August 31, 1998
--------------------------------------      Financial Officer (Principal                            
Phillip M. Schneider                        Financial and Accounting Officer)
II-4
6
Signatures                                  Title                                             Date
----------                                  -----                                             ----
/S/CHARLES C. EDWARDS, M.D.                 Director                                          August 31, 1998
--------------------------------------                                                              
Charles C. Edwards, M.D.

/S/ALAN B. GLASSBERG, M.D.                  Director                                          August 31, 1998
--------------------------------------                                                              
Alan B. Glassberg, M.D.

                                            Director                                          August   , 1998
--------------------------------------                                                              ----
John Groom

                                            Director                                          August   , 1998
--------------------------------------                                                              ----
Kazuhiro Hashimoto

/S/FRANKLIN P. JOHNSON, JR.                 Director                                          August 31, 1998
--------------------------------------                                                              
Franklin P. Johnson, Jr.

/S/LYNN SCHENK                              Director                                          August 31, 1998
--------------------------------------                                                             
Lynn Schenk

/S/WILLIAM D. YOUNG                         Director                                          August 31, 1998
--------------------------------------                                                              
William D. Young

/S/ROBERT W. PANGIA                         Director                                          August 31, 1998
--------------------------------------                                                              
Robert W. Pangia

/S/BRUCE R. ROSS                            Director                                          August 31, 1998
--------------------------------------                                                              
Bruce R. Ross
II-5
7

                                  EXHIBIT INDEX
Exhibit Number         Exhibit
   --------------         -------
4                    Instruments Defining Rights of Stockholders.  Reference is made to Registrant's Registration
                          Statement No. 0-19311 on Form 8-B, including exhibits thereto, which is incorporated herein
                          by reference pursuant to Item 3(c).
     5.1                  Opinion of Brobeck, Phleger & Harrison LLP.
     23.1                 Consent of Independent Auditors - KPMG Peat Marwick LLP.
     23.2                 Consent of Brobeck, Phleger & Harrison LLP is contained in Exhibit 5.1.
     24                   Power of Attorney.  Reference is made to page II-4 of this Registration Statement.
     99.1                 Amended and Restated 1988 Stock Option Plan (Amended and Restated February 20, 1998).
     99.2*                Form of Notice of Grant.
     99.3*                Form of Stock Option Agreement.
     99.4                 1993 Non-Employee Directors Stock Option Plan (Amended and Restated February 20, 1998).
     99.5**               Form of Notice of Grant of Automatic Stock Option (New Director).
     99.6**               Form of Notice of Grant of Automatic Stock Option (Continuing Director).
     99.7**               Form of Stock Option Agreement.
*    Exhibits 99.2 and 99.3 are incorporated herein by reference to Exhibits
     28.2 and 28.3, respectively, of Registrant's Registration Statement No.
     33-45172 on Form S-8 which was filed with the Commission on January 21,
     1992.

**   Exhibits 99.5, 99.6 and 99.7 are incorporated herein by reference to
     Exhibits 99.2, 99.3 and 99.4, respectively, of Registrant's Registration
     Statement No. 33-93794 on Form S-8 which was filed with the Commission on
     June 25, 1995.