<PAGE>   1
     AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON AUGUST 20, 1999
                                                           REGISTRATION NO. 333-
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                           ---------------------------


                                    FORM S-8
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

                          ARONEX PHARMACEUTICALS, INC.
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)


                   DELAWARE                               76-0196535
       (STATE OR OTHER JURISDICTION OF                 (I.R.S. EMPLOYER
        INCORPORATION OR ORGANIZATION)               IDENTIFICATION NO.)

         8707 TECHNOLOGY FOREST PLACE
             THE WOODLANDS, TEXAS                         77381-1191
   (ADDRESS OF PRINCIPAL EXECUTIVE OFFICES)               (ZIP CODE)

                  AMENDED AND RESTATED 1989 STOCK OPTION PLAN,
                     AMENDED AND RESTATED 1993 NON-EMPLOYEE
                           DIRECTOR STOCK OPTION PLAN
                                       AND
                             1998 STOCK OPTION PLAN
                           (FULL TITLES OF THE PLANS)

                               TERANCE A. MURNANE
                            CONTROLLER AND SECRETARY
                          ARONEX PHARMACEUTICALS, INC.
                          8707 TECHNOLOGY FOREST PLACE
                         THE WOODLANDS, TEXAS 77381-1191
                     (NAME AND ADDRESS OF AGENT FOR SERVICE)
                                 (281) 367-1666
          (TELEPHONE NUMBER, INCLUDING AREA CODE, OF AGENT FOR SERVICE)
                           ---------------------------

                                    COPY TO:
                                JEFFREY R. HARDER
                             ANDREWS & KURTH L.L.P.
                        2170 BUCKTHORNE PLACE, SUITE 150
                           THE WOODLANDS, TEXAS 77380
                                 (713) 220-4801
                           ---------------------------


                         CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
                                                                                 PROPOSED          PROPOSED
                                                                                  MAXIMUM           MAXIMUM
                                                               AMOUNT TO      OFFERING PRICE       AGGREGATE         AMOUNT OF
TITLE OF SECURITIES TO BE REGISTERED    TITLE OF PLAN       BE REGISTERED(1)   PER SHARE(2)    OFFERING PRICE(2) REGISTRATION FEE
------------------------------------ --------------------- ----------------- ----------------- ----------------- -----------------

<S>                                 <C>                    <C>               <C>               <C>               <C>
Common Stock, par value $.001 per   Amended and  Restated
share ("Common Stock")              1989 Stock Option
                                    Plan                   3,073,980 shares(3) $   4.09          $  12,572,578     $      3,495.18

Common Stock                        Amended and Restated
                                    1993 Non-Employee
                                    Director Stock Option
                                    Plan                     350,000 shares(4) $   4.09          $   1,431,500     $        397.96
--------------------------------- ------------------------ ----------------- ----------------- ----------------- -----------------
Common Stock                        1998 Stock Option Plan   750,000 shares    $   4.09          $   3,067,500     $        852.77
================================= ======================== ================= ================= ================= =================
</TABLE>

(1)      Pursuant to Rule 416(a), this registration statement shall cover any
         additional securities issued to prevent dilution resulting from stock
         splits, stock dividends or similar transactions.
(2)      Estimated solely for the purpose of calculating the registration fee
         pursuant to Rule 457 (c) and (h), based on the average of the high and
         low sales price per share of the registrant's common stock, as reported
         on The Nasdaq Stock Market on August 16, 1999.
(3)      Initially, 750,000 shares were registered under this plan. It has since
         been amended and currently 3,823,980 shares are reserved for issuance
         under this plan.
(4)      Initially, 250,000 shares were registered under this plan. It has since
         been amended and currently 600,000 shares are reserved for issuance
         under this plan.

================================================================================

<PAGE>   2

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT


ITEM 3.   INCORPORATION OF DOCUMENTS BY REFERENCE.

         Aronex Pharmaceuticals, Inc. (the "Company") incorporates herein by
reference the following documents, as filed with the Securities and Exchange
Commission (the "Commission"), as of their respective filing dates:

                  (a) The Company's Annual Report on Form 10-K (File No.
         0-21198) for the year ended December 31, 1998;

                  (b) The Company's Quarterly Reports on Form 10-Q for the
         quarters ended March 31, 1999 and June 30, 1999;

                  (c) The description of the Company's common stock, par value
         $0.001 per share, contained in the Company's registration statement on
         Form 8-A filed with the Commission on April 23, 1992, including any
         amendments and reports filed for the purpose of updating such
         description.

         All documents filed by the Company pursuant to Section 13(a), 13(c), 14
and 15(d) of the Securities Exchange Act of 1934, as amended (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 such securities then remaining unsold
shall be deemed to be incorporated by reference in this registration statement
and to be a part hereof from the date of filing such documents.

ITEM 4.  DESCRIPTION OF SECURITIES.

         The information required by Item 4 is not applicable to this
registration statement because the class of securities to be offered is
registered under Section 12 of the Exchange Act.

ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL.

         The information required by Item 5 is not applicable to this
registration statement.

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS.

         Section 145 of the Delaware General Corporation Law ("DGCL"), inter
alia, empowers a Delaware corporation to indemnify any person who was or is a
party or is threatened to be made a party to any threatened, pending or
completed action, suit or proceeding (other than an action by or in the right of
the corporation) by reason of the fact that such person is or was a director,
officer, employee or agent of the corporation, or is or was serving at the
request of the corporation as a director, officer, employee or agent of another
corporation or other enterprise, against expenses (including attorneys' fees),
judgments, fines and amounts paid in settlement actually and reasonably incurred
by him in connection with such action, suit or proceeding if he acted in good
faith and in a manner he reasonably believed to be in or not opposed to the best
interests of the corporation, and, with respect to any criminal action or
proceeding, had no reasonable cause to believe his conduct was unlawful. Similar
indemnity is authorized for such persons against expenses (including attorneys'
fees) actually and reasonably incurred in connection with the defense or
settlement of any such threatened, pending or completed action or suit if such
person acted in good faith and in a manner he reasonably believed to be in or
not opposed to the best interests of the corporation, and provided further that
(unless a court of competent jurisdiction otherwise provides) such person shall
not have been adjudged liable to the corporation. Any such indemnification may
be made only as authorized in each specific case upon a determination by the
stockholders or disinterested directors or by independent legal counsel in a
written opinion that indemnification is proper because the indemnitee has met
the applicable standard of conduct.

         Section 145 further authorizes a corporation to purchase and maintain
insurance on behalf of any person who is or was a director, officer, employee or
agent of the corporation, or is or was serving at the request of the corporation
as a director, officer, employee or agent of another corporation or enterprise,
against any liability asserted against him and incurred by him in any such
capacity, or arising out of his status as such, whether or not the corporation
would otherwise have the power to indemnify him under Section 145. The Company
maintains policies insuring its and its subsidiaries' officers and directors
against certain liabilities for actions taken in such capacities, including
liabilities under the Securities Act of 1933, as amended (the "Securities Act").



                                       -1-

<PAGE>   3



         Article VIII of the Amended and Restated Certificate of Incorporation
of the Company and Article VII of the Bylaws of the Company provide for
indemnification of the directors of the Company to the fullest extent permitted
by law, as now in effect or later amended. Article VII of the Bylaws also
permits the indemnification to the same extent of officers, employees or agents
of the Company if, and to the extent, authorized by the Board of Directors. In
addition, the Bylaws provide for indemnification against expenses incurred by a
director to be paid by the Company at reasonable intervals in advance of the
final disposition of such action, suit or proceeding upon receipt of an
undertaking by or on behalf of the director or officer to repay such amount if
it shall be ultimately determined that he is not entitled to be indemnified by
the Company. The Bylaws further provide for a contractual cause of action on the
part of directors of the Company for indemnification claims that have not been
paid by the Company.

         The Company also has provided liability insurance for each director and
officer for certain losses arising from claims or charges made against them
while acting in their capacities as directors or officers of the Company.

         Article VII of the Company's Amended and Restated Certificate of
Incorporation, as amended, limits under certain circumstances the liability of
the Company's directors for a breach of their fiduciary duty as directors. These
provisions do not eliminate the liability of a director (i) for a breach of the
director's duty of loyalty to the Company or its stockholders, (ii) for acts or
omissions not in good faith or that involve intentional misconduct or a knowing
violation of law, (iii) under Section 174 of the DGCL (relating to the
declaration of dividends and purchase or redemption of shares in violation of
the DGCL) or (iv) for any transaction from which the director derived an
improper personal benefit.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED.

         The information required by Item 7 is not applicable to this
registration statement.

ITEM 8.  EXHIBITS.

    Exhibit
    Number       Description

     4.1+        Restated Certificate of Incorporation (incorporated by
                 reference to Exhibit 3.1 to the Company's Quarterly Report on
                 Form 10-Q for the fiscal quarter ended June 30, 1997 (the "1997
                 2nd Quarter Form 10-Q")).

     4.2+        Restated Bylaws (incorporated by reference to Exhibit 3.2 to
                 the Company's Registration Statement on Form S-1 (No.
                 33-47418), declared effective by the Commission on July 10,
                 1992).

     4.3+        Specimen Common Stock Certificate (incorporated by reference to
                 Exhibit 4.1 to the Company's Quarterly Report on Form 10-Q for
                 the fiscal quarter ended June 30, 1996).

     5.1*        Opinion of Andrews & Kurth L.L.P.

    10.1+        Aronex Pharmaceuticals, Inc. Amended and Restated 1989 Stock
                 Option Plan (incorporated by reference to Exhibit 10.1 to the
                 1997 2nd Quarter Form 10-Q).

    10.2+        Aronex Pharmaceuticals, Inc. Amended and Restated 1993
                 Non-Employee Director Stock Option Plan (incorporated by
                 reference to Exhibit 10.2 to the 1997 2nd Quarter Form 10-Q).

    10.3+        Aronex Pharmaceuticals, Inc. 1998 Stock Option Plan
                 (incorporated by reference to Exhibit 10.1 to the Company's
                 Quarterly Report on Form 10-Q for the fiscal quarter ended June
                 30, 1998).

    23.1*        Consent of Andrews & Kurth L.L.P. (included in Exhibit 5.1).

    23.2*        Consent of Arthur Andersen LLP

    24.1*        Power of Attorney (set forth on the signature page contained in
                 Part II of this Registration Statement).

---------------------------

+ Incorporated herein by reference.
* Filed herewith.



                                       -2-

<PAGE>   4

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 Securities 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;

                           (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 paragraphs (a)(1)(i) and (a)(1)(ii) above do
         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 Company pursuant to Section 13 or Section 15(d) of
         the Exchange Act that are incorporated by reference in the registration
         statement.

                  (2) That, for the purpose of determining any liability under
         the Securities 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.

                  (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 offering.

         (b) The undersigned registrant hereby undertakes that, for purposes of
determining any liability under the Exchange Act, each filing of the Company's
annual report pursuant to Section 13(a) or 15(d) of the Exchange Act that is
incorporated by reference in 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
Securities Act may be permitted to directors, officers and controlling persons
of the Company pursuant to the foregoing provisions, or otherwise, the Company
has been advised that in the opinion of the Commission such indemnification is
against public policy as expressed in the Securities Act and is, therefore,
unenforceable. In the event that a claim for indemnification against such
liabilities (other than the payment by the Company of expenses incurred or paid
by a director, officer or controlling person of the Company 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
Company 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 Securities Act and will be governed by the final adjudication
of such issue.



                                       -3-

<PAGE>   5

                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, 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 Woodlands, Texas, on the 20th day of August, 1999.

                                     ARONEX PHARMACEUTICALS, INC.


                                     By:   /s/ Geoffrey F. Cox
                                         ---------------------------------------
                                               Geoffrey F. Cox
                                               Chairman of the Board and Chief
                                                Executive Officer


                                POWER OF ATTORNEY

         KNOW ALL MEN BY THESE PRESENTS, that each of the undersigned officers
and directors of Aronex Pharmaceuticals, Inc. (the "Company") hereby constitutes
and appoints Geoffrey F. Cox and Terance A. Murnane, and each of them (with full
power to each of them to act alone), his true and lawful attorney-in-fact and
agent, with full power of substitution, for him and on his behalf and in his
name, place and stead, in any and all capacities, to sign, execute and file this
registration statement under the Securities Act of 1933, as amended, and any or
all amendments (including, without limitation, post-effective amendments), with
all exhibits and any and all documents required to be filed with respect
thereto, with the Securities and Exchange Commission or any regulatory
authority, granting unto such attorneys-in-fact and agents, and each of them,
full power and authority to do and perform each and every act and thing
requisite and necessary to be done in order to effectuate the same, as fully to
all intents and purposes as he himself might or could do if personally present,
hereby ratifying and confirming all that such attorneys-in-fact and agents, or
any of them, or their substitute or substitutes, may lawfully do or cause to be
done.

         PURSUANT TO THE REQUIREMENTS OF THE SECURITIES ACT OF 1933, THIS
REGISTRATION STATEMENT HAS BEEN SIGNED BY THE FOLLOWING PERSONS IN THE
CAPACITIES AND ON THE DATES INDICATED.


<TABLE>
<CAPTION>
                 SIGNATURE                                        TITLE                               DATE

<S>                                            <C>                                            <C>
    /s/ Geoffrey F. Cox                        Chairman of the Board of Directors and Chief   August 20, 1999
---------------------------------------                     Executive Officer
        Geoffrey F. Cox                               (Principal Executive Officer)

    /s/ Terance A. Murnane                                      Controller                    August 20, 1999
---------------------------------------                  (Principal Financial and
        Terance A. Murnane                                  Accounting Officer)

                                                                  Director                     August 20, 1999
---------------------------------------
        James R. Butler

    /s/ Paul W. Hobby                                             Director                     August 20, 1999
---------------------------------------
        Paul W. Hobby

                                                                  Director                     August 20, 1999
---------------------------------------
        Gabriel Lopez-Berestein

    /s/ David J. McLachlan                                        Director                     August 20, 1999
---------------------------------------
        David J. McLachlan

    /s/ Martin P. Sutter                                          Director                     August 20, 1999
---------------------------------------
        Martin P. Sutter

    /s/ Gregory F. Zaic                                           Director                     August 20, 1999
---------------------------------------
        Gregory F. Zaic

    /s/ Phyllis I.  Gardner                                      Director                     August 20, 1999
---------------------------------------
       Phyllis I.  Gardner
</TABLE>



<PAGE>   6

                                  EXHIBIT INDEX


<TABLE>
<CAPTION>
    Exhibit
    Number      Description
    -------     -----------

<S>             <C>
     4.1+       Restated Certificate of Incorporation (incorporated by reference to Exhibit 3.1 to the Company's
                Quarterly Report on Form 10-Q for the fiscal quarter ended June 30, 1997 (the "1997 2nd Quarter
                Form 10-Q")).

     4.2+       Restated Bylaws (incorporated by reference to Exhibit 3.2 to the Company's Registration Statement
                on Form S-1 (No. 33-47418), declared effective by the Commission on July 10, 1992).

     4.3+       Specimen Common Stock Certificate (incorporated by reference to Exhibit 4.1 to the Company's
                Quarterly Report on Form 10-Q for the fiscal quarter ended June 30, 1996).

     5.1*       Opinion of Andrews & Kurth L.L.P.

    10.1+       Aronex Pharmaceuticals, Inc. Amended and Restated 1989 Stock Option Plan (incorporated by
                reference to Exhibit 10.1 to the 1997 2nd Quarter Form 10-Q).

    10.2+       Aronex Pharmaceuticals, Inc. Amended and Restated 1993 Non-Employee Director Stock Option Plan
                (incorporated by reference to Exhibit 10.2 to the 1997 2nd Quarter Form 10-Q).

    10.3+       Aronex Pharmaceuticals, Inc. 1998 Stock Option Plan (incorporated by reference to Exhibit 10.1 to
                the Company's Quarterly Report on Form 10-Q for the fiscal quarter ended June 30, 1998).

    23.1*       Consent of Andrews & Kurth L.L.P. (included in Exhibit 5.1).

    23.2*       Consent of Arthur Andersen LLP.

    24.1*       Power of Attorney (set forth on the signature page contained in Part II of this Registration Statement).
</TABLE>

---------------------------

+ Incorporated herein by reference.
* Filed herewith.
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{"company-data": {"conformed-name": "ARONEX PHARMACEUTICALS INC", "cik": "0000854691", "assigned-sic": "2834", "irs-number": "760196535", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-85615", "film-number": "99696556"}, "business-address": {"street1": "8707 TECHNOLOGY FOREST PLACE", "city": "THE WOODLANDS", "state": "TX", "zip": "77381-1191", "phone": "2813671666"}, "mail-address": {"street1": "8707 TECHNOLOGY FOREST PLACE", "city": "THE WOODLANDS", "state": "TX", "zip": "77381-1191"}}
1
     AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON AUGUST 20, 1999
                                                           REGISTRATION NO. 333-
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                           ---------------------------

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

                          ARONEX PHARMACEUTICALS, INC.
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)

                   DELAWARE                               76-0196535
       (STATE OR OTHER JURISDICTION OF                 (I.R.S. EMPLOYER
        INCORPORATION OR ORGANIZATION)               IDENTIFICATION NO.)

         8707 TECHNOLOGY FOREST PLACE
             THE WOODLANDS, TEXAS                         77381-1191
   (ADDRESS OF PRINCIPAL EXECUTIVE OFFICES)               (ZIP CODE)

                  AMENDED AND RESTATED 1989 STOCK OPTION PLAN,
                     AMENDED AND RESTATED 1993 NON-EMPLOYEE
                           DIRECTOR STOCK OPTION PLAN
                                       AND
                             1998 STOCK OPTION PLAN
                           (FULL TITLES OF THE PLANS)

                               TERANCE A. MURNANE
                            CONTROLLER AND SECRETARY
                          ARONEX PHARMACEUTICALS, INC.
                          8707 TECHNOLOGY FOREST PLACE
                         THE WOODLANDS, TEXAS 77381-1191
                     (NAME AND ADDRESS OF AGENT FOR SERVICE)
                                 (281) 367-1666
          (TELEPHONE NUMBER, INCLUDING AREA CODE, OF AGENT FOR SERVICE)
                           ---------------------------

                                    COPY TO:
                                JEFFREY R. HARDER
                             ANDREWS & KURTH L.L.P.
                        2170 BUCKTHORNE PLACE, SUITE 150
                           THE WOODLANDS, TEXAS 77380
                                 (713) 220-4801
                           ---------------------------

                         CALCULATION OF REGISTRATION FEE
PROPOSED          PROPOSED
                                                                                  MAXIMUM           MAXIMUM
                                                               AMOUNT TO      OFFERING PRICE       AGGREGATE         AMOUNT OF
TITLE OF SECURITIES TO BE REGISTERED    TITLE OF PLAN       BE REGISTERED(1)   PER SHARE(2)    OFFERING PRICE(2) REGISTRATION FEE
------------------------------------ --------------------- ----------------- ----------------- ----------------- -----------------
Common Stock, par value $.001 per   Amended and  Restated
share ("Common Stock")              1989 Stock Option
                                    Plan                   3,073,980 shares(3) $   4.09          $  12,572,578     $      3,495.18

Common Stock                        Amended and Restated
                                    1993 Non-Employee
                                    Director Stock Option
                                    Plan                     350,000 shares(4) $   4.09          $   1,431,500     $        397.96
--------------------------------- ------------------------ ----------------- ----------------- ----------------- -----------------
Common Stock                        1998 Stock Option Plan   750,000 shares    $   4.09          $   3,067,500     $        852.77
================================= ======================== ================= ================= ================= =================
(1)      Pursuant to Rule 416(a), this registration statement shall cover any
         additional securities issued to prevent dilution resulting from stock
         splits, stock dividends or similar transactions.
(2)      Estimated solely for the purpose of calculating the registration fee
         pursuant to Rule 457 (c) and (h), based on the average of the high and
         low sales price per share of the registrant's common stock, as reported
         on The Nasdaq Stock Market on August 16, 1999.
(3)      Initially, 750,000 shares were registered under this plan. It has since
         been amended and currently 3,823,980 shares are reserved for issuance
         under this plan.
(4)      Initially, 250,000 shares were registered under this plan. It has since
         been amended and currently 600,000 shares are reserved for issuance
         under this plan.

================================================================================
2

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.   INCORPORATION OF DOCUMENTS BY REFERENCE.

         Aronex Pharmaceuticals, Inc. (the "Company") incorporates herein by
reference the following documents, as filed with the Securities and Exchange
Commission (the "Commission"), as of their respective filing dates:

                  (a) The Company's Annual Report on Form 10-K (File No.
         0-21198) for the year ended December 31, 1998;

                  (b) The Company's Quarterly Reports on Form 10-Q for the
         quarters ended March 31, 1999 and June 30, 1999;

                  (c) The description of the Company's common stock, par value
         $0.001 per share, contained in the Company's registration statement on
         Form 8-A filed with the Commission on April 23, 1992, including any
         amendments and reports filed for the purpose of updating such
         description.

         All documents filed by the Company pursuant to Section 13(a), 13(c), 14
and 15(d) of the Securities Exchange Act of 1934, as amended (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 such securities then remaining unsold
shall be deemed to be incorporated by reference in this registration statement
and to be a part hereof from the date of filing such documents.

ITEM 4.  DESCRIPTION OF SECURITIES.

         The information required by Item 4 is not applicable to this
registration statement because the class of securities to be offered is
registered under Section 12 of the Exchange Act.

ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL.

         The information required by Item 5 is not applicable to this
registration statement.

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS.

         Section 145 of the Delaware General Corporation Law ("DGCL"), inter
alia, empowers a Delaware corporation to indemnify any person who was or is a
party or is threatened to be made a party to any threatened, pending or
completed action, suit or proceeding (other than an action by or in the right of
the corporation) by reason of the fact that such person is or was a director,
officer, employee or agent of the corporation, or is or was serving at the
request of the corporation as a director, officer, employee or agent of another
corporation or other enterprise, against expenses (including attorneys' fees),
judgments, fines and amounts paid in settlement actually and reasonably incurred
by him in connection with such action, suit or proceeding if he acted in good
faith and in a manner he reasonably believed to be in or not opposed to the best
interests of the corporation, and, with respect to any criminal action or
proceeding, had no reasonable cause to believe his conduct was unlawful. Similar
indemnity is authorized for such persons against expenses (including attorneys'
fees) actually and reasonably incurred in connection with the defense or
settlement of any such threatened, pending or completed action or suit if such
person acted in good faith and in a manner he reasonably believed to be in or
not opposed to the best interests of the corporation, and provided further that
(unless a court of competent jurisdiction otherwise provides) such person shall
not have been adjudged liable to the corporation. Any such indemnification may
be made only as authorized in each specific case upon a determination by the
stockholders or disinterested directors or by independent legal counsel in a
written opinion that indemnification is proper because the indemnitee has met
the applicable standard of conduct.

         Section 145 further authorizes a corporation to purchase and maintain
insurance on behalf of any person who is or was a director, officer, employee or
agent of the corporation, or is or was serving at the request of the corporation
as a director, officer, employee or agent of another corporation or enterprise,
against any liability asserted against him and incurred by him in any such
capacity, or arising out of his status as such, whether or not the corporation
would otherwise have the power to indemnify him under Section 145. The Company
maintains policies insuring its and its subsidiaries' officers and directors
against certain liabilities for actions taken in such capacities, including
liabilities under the Securities Act of 1933, as amended (the "Securities Act").

                                       -1-
3

         Article VIII of the Amended and Restated Certificate of Incorporation
of the Company and Article VII of the Bylaws of the Company provide for
indemnification of the directors of the Company to the fullest extent permitted
by law, as now in effect or later amended. Article VII of the Bylaws also
permits the indemnification to the same extent of officers, employees or agents
of the Company if, and to the extent, authorized by the Board of Directors. In
addition, the Bylaws provide for indemnification against expenses incurred by a
director to be paid by the Company at reasonable intervals in advance of the
final disposition of such action, suit or proceeding upon receipt of an
undertaking by or on behalf of the director or officer to repay such amount if
it shall be ultimately determined that he is not entitled to be indemnified by
the Company. The Bylaws further provide for a contractual cause of action on the
part of directors of the Company for indemnification claims that have not been
paid by the Company.

         The Company also has provided liability insurance for each director and
officer for certain losses arising from claims or charges made against them
while acting in their capacities as directors or officers of the Company.

         Article VII of the Company's Amended and Restated Certificate of
Incorporation, as amended, limits under certain circumstances the liability of
the Company's directors for a breach of their fiduciary duty as directors. These
provisions do not eliminate the liability of a director (i) for a breach of the
director's duty of loyalty to the Company or its stockholders, (ii) for acts or
omissions not in good faith or that involve intentional misconduct or a knowing
violation of law, (iii) under Section 174 of the DGCL (relating to the
declaration of dividends and purchase or redemption of shares in violation of
the DGCL) or (iv) for any transaction from which the director derived an
improper personal benefit.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED.

         The information required by Item 7 is not applicable to this
registration statement.

ITEM 8.  EXHIBITS.

    Exhibit
    Number       Description

     4.1+        Restated Certificate of Incorporation (incorporated by
                 reference to Exhibit 3.1 to the Company's Quarterly Report on
                 Form 10-Q for the fiscal quarter ended June 30, 1997 (the "1997
                 2nd Quarter Form 10-Q")).

     4.2+        Restated Bylaws (incorporated by reference to Exhibit 3.2 to
                 the Company's Registration Statement on Form S-1 (No.
                 33-47418), declared effective by the Commission on July 10,
                 1992).

     4.3+        Specimen Common Stock Certificate (incorporated by reference to
                 Exhibit 4.1 to the Company's Quarterly Report on Form 10-Q for
                 the fiscal quarter ended June 30, 1996).

     5.1*        Opinion of Andrews & Kurth L.L.P.

    10.1+        Aronex Pharmaceuticals, Inc. Amended and Restated 1989 Stock
                 Option Plan (incorporated by reference to Exhibit 10.1 to the
                 1997 2nd Quarter Form 10-Q).

    10.2+        Aronex Pharmaceuticals, Inc. Amended and Restated 1993
                 Non-Employee Director Stock Option Plan (incorporated by
                 reference to Exhibit 10.2 to the 1997 2nd Quarter Form 10-Q).

    10.3+        Aronex Pharmaceuticals, Inc. 1998 Stock Option Plan
                 (incorporated by reference to Exhibit 10.1 to the Company's
                 Quarterly Report on Form 10-Q for the fiscal quarter ended June
                 30, 1998).

    23.1*        Consent of Andrews & Kurth L.L.P. (included in Exhibit 5.1).

    23.2*        Consent of Arthur Andersen LLP

    24.1*        Power of Attorney (set forth on the signature page contained in
                 Part II of this Registration Statement).

---------------------------

+ Incorporated herein by reference.
* Filed herewith.

                                       -2-
4

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 Securities 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;

                           (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 paragraphs (a)(1)(i) and (a)(1)(ii) above do
         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 Company pursuant to Section 13 or Section 15(d) of
         the Exchange Act that are incorporated by reference in the registration
         statement.

                  (2) That, for the purpose of determining any liability under
         the Securities 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.

                  (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 offering.

         (b) The undersigned registrant hereby undertakes that, for purposes of
determining any liability under the Exchange Act, each filing of the Company's
annual report pursuant to Section 13(a) or 15(d) of the Exchange Act that is
incorporated by reference in 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
Securities Act may be permitted to directors, officers and controlling persons
of the Company pursuant to the foregoing provisions, or otherwise, the Company
has been advised that in the opinion of the Commission such indemnification is
against public policy as expressed in the Securities Act and is, therefore,
unenforceable. In the event that a claim for indemnification against such
liabilities (other than the payment by the Company of expenses incurred or paid
by a director, officer or controlling person of the Company 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
Company 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 Securities Act and will be governed by the final adjudication
of such issue.

                                       -3-
5

                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, 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 Woodlands, Texas, on the 20th day of August, 1999.

                                     ARONEX PHARMACEUTICALS, INC.

                                     By:   /s/ Geoffrey F. Cox
                                         ---------------------------------------
                                               Geoffrey F. Cox
                                               Chairman of the Board and Chief
                                                Executive Officer

                                POWER OF ATTORNEY

         KNOW ALL MEN BY THESE PRESENTS, that each of the undersigned officers
and directors of Aronex Pharmaceuticals, Inc. (the "Company") hereby constitutes
and appoints Geoffrey F. Cox and Terance A. Murnane, and each of them (with full
power to each of them to act alone), his true and lawful attorney-in-fact and
agent, with full power of substitution, for him and on his behalf and in his
name, place and stead, in any and all capacities, to sign, execute and file this
registration statement under the Securities Act of 1933, as amended, and any or
all amendments (including, without limitation, post-effective amendments), with
all exhibits and any and all documents required to be filed with respect
thereto, with the Securities and Exchange Commission or any regulatory
authority, granting unto such attorneys-in-fact and agents, and each of them,
full power and authority to do and perform each and every act and thing
requisite and necessary to be done in order to effectuate the same, as fully to
all intents and purposes as he himself might or could do if personally present,
hereby ratifying and confirming all that such attorneys-in-fact and agents, or
any of them, or their substitute or substitutes, may lawfully do or cause to be
done.

         PURSUANT TO THE REQUIREMENTS OF THE SECURITIES ACT OF 1933, THIS
REGISTRATION STATEMENT HAS BEEN SIGNED BY THE FOLLOWING PERSONS IN THE
CAPACITIES AND ON THE DATES INDICATED.
SIGNATURE                                        TITLE                               DATE
/s/ Geoffrey F. Cox                        Chairman of the Board of Directors and Chief   August 20, 1999
---------------------------------------                     Executive Officer
        Geoffrey F. Cox                               (Principal Executive Officer)

    /s/ Terance A. Murnane                                      Controller                    August 20, 1999
---------------------------------------                  (Principal Financial and
        Terance A. Murnane                                  Accounting Officer)

                                                                  Director                     August 20, 1999
---------------------------------------
        James R. Butler

    /s/ Paul W. Hobby                                             Director                     August 20, 1999
---------------------------------------
        Paul W. Hobby

                                                                  Director                     August 20, 1999
---------------------------------------
        Gabriel Lopez-Berestein

    /s/ David J. McLachlan                                        Director                     August 20, 1999
---------------------------------------
        David J. McLachlan

    /s/ Martin P. Sutter                                          Director                     August 20, 1999
---------------------------------------
        Martin P. Sutter

    /s/ Gregory F. Zaic                                           Director                     August 20, 1999
---------------------------------------
        Gregory F. Zaic

    /s/ Phyllis I.  Gardner                                      Director                     August 20, 1999
---------------------------------------
       Phyllis I.  Gardner
6

                                  EXHIBIT INDEX
Exhibit
    Number      Description
    -------     -----------
4.1+       Restated Certificate of Incorporation (incorporated by reference to Exhibit 3.1 to the Company's
                Quarterly Report on Form 10-Q for the fiscal quarter ended June 30, 1997 (the "1997 2nd Quarter
                Form 10-Q")).

     4.2+       Restated Bylaws (incorporated by reference to Exhibit 3.2 to the Company's Registration Statement
                on Form S-1 (No. 33-47418), declared effective by the Commission on July 10, 1992).

     4.3+       Specimen Common Stock Certificate (incorporated by reference to Exhibit 4.1 to the Company's
                Quarterly Report on Form 10-Q for the fiscal quarter ended June 30, 1996).

     5.1*       Opinion of Andrews & Kurth L.L.P.

    10.1+       Aronex Pharmaceuticals, Inc. Amended and Restated 1989 Stock Option Plan (incorporated by
                reference to Exhibit 10.1 to the 1997 2nd Quarter Form 10-Q).

    10.2+       Aronex Pharmaceuticals, Inc. Amended and Restated 1993 Non-Employee Director Stock Option Plan
                (incorporated by reference to Exhibit 10.2 to the 1997 2nd Quarter Form 10-Q).

    10.3+       Aronex Pharmaceuticals, Inc. 1998 Stock Option Plan (incorporated by reference to Exhibit 10.1 to
                the Company's Quarterly Report on Form 10-Q for the fiscal quarter ended June 30, 1998).

    23.1*       Consent of Andrews & Kurth L.L.P. (included in Exhibit 5.1).

    23.2*       Consent of Arthur Andersen LLP.

    24.1*       Power of Attorney (set forth on the signature page contained in Part II of this Registration Statement).
---------------------------

+ Incorporated herein by reference.
* Filed herewith.