CONSULTING AGREEMENT

          This  Consulting  Agreement is made and entered into as of the 1st day
of  January,  1998,  by and between  Aronex  Pharmaceuticals,  Inc.,  a Delaware
corporation  (hereinafter referred to as "Company") and Gabriel  Lopez-Berestein
(hereinafter referred to as a "Consultant").

          WHEREAS, Consultant desires to provide special expertise and knowledge
to Company in the area of  biochemistry  and/or drug  development and to consult
with  Company on such  specific  research  projects in the area as may be agreed
upon from time to time in writing  between  the Company  and  Consultant,  which
written  agreement(s) shall be incorporated  herein by reference and made a part
hereof (hereinafter "Consulting Subjects"); and

          WHEREAS,  Company  desires  to  retain  Consultant  as an  independent
contractor  upon the  terms and  conditions  hereinafter  set  forth to  provide
consulting  and  advisory  services  to Company  based on  Consultant's  special
knowledge and expertise in the Consulting Subjects;

          NOW,  THEREFORE,  for and in consideration of the mutual covenants and
promises  and  representations  contained  herein,  and other good and  valuable
consideration,  the receipt and  sufficiency  of which are hereby  acknowledged,
Company and Consultant agree as follows:

          1. Expertise of Consultant.

          1.1 Consultant  represents that he has special expertise and knowledge
concerning  the  Consulting  Subjects  and that he is  willing  to and wishes to
provide his  consultation  and advisory  services to Company in connection  with
such area or areas.

          1.2  Consultant   hereby  represents  and  warrants  to  Company  that
Consultant  is not a party to any  agreement  with any other  entity  and is not
bound by any  obligations  to any other  entity  which will  prevent or encumber
Consultant  from  performing  such  services  for  Company,   except  for  those
agreements, if any, identified on Exhibit A hereto and approved by the Company.

          2. Independent Contractor.

          2.1 Consultant  hereby agrees to perform for Company or any affiliate,
parent or  subsidiary  of Company  and to  provide to Company or any  affiliate,
parent or subsidiary of Company his personal  consultation and advisory services
in the Consulting  Subjects in accordance with the terms of this  Agreement.  To
the extent  services  pursuant to this  Agreement  are  performed  for or at the
request of an  affiliate,  parent,  or  subsidiary,  the term  "Company" as used
herein shall include such entity.

          2.2 Throughout the entire term of this Agreement,  Consultant shall be
an independent contractor with the full power and authority to select the means,
method and manner of performing his services hereunder;  provided, however, that
Consultant  will perform  consulting and advisory or other services in the areas
designated by Company.  Consultant  will in no way be considered to be an agent,
employee  or servant of  Company.  Consultant  shall have no  authority  to bind
Company in any capacity for any purpose.

          2.3 It is not  the  purpose  or  intention  of this  Agreement  or the
parties  to  create,  and the same  shall  not be  construed  as  creating,  any
partnership,  joint venture,  agency, or employment  relationship.  However,  as
specified below, due to the nature of this independent contractor  relationship,
it is the  intent  of the  parties  that,  during  the  term of this  Agreement,
Consultant  shall owe to  Company  fiduciary  duties of the utmost  loyalty  and
fidelity.
<PAGE>

          3. General Duties and Compensation.

          3.1 During the term of this Agreement, Consultant shall, at such times
and locations as are reasonably  requested by Company and at either the Company,
The  University  of Texas System Cancer  Center and M.D.  Anderson  Hospital and
Tumor  Institute  or such other  location  agreed upon  between  Consultant  and
Company, provide personal consultation and advisory services as may from time to
time be agreed upon between the Company and  Consultant,  perform and  supervise
the  performance by others of research with respect to (a) Consulting  Subjects,
and (b) any other  areas of interest  upon which  Consultant  and Company  shall
mutually  agree.  Consultant  shall  be so  available  during  the  term of this
Agreement  for such  periods  as may be agreed  upon  from time to time  between
Company and Consultant, as and when specific research projects are agreed upon.

          3.2 For the  performance  of his  obligations  under  this  Agreement,
Company  shall pay the  Consultant  a fee at the rate of  $156,000.00  per year,
one-half  of which  shall be  payable  in cash and  one-half  of which  shall be
payable in the form of a grant of the Company's  Common Stock.  The cash portion
of such fee shall be payable  monthly  on the 15th day of each month  during the
term of this  Agreement.  The Common Stock portion of such fee for each calendar
year during the term of this Agreement  shall be payable on January 15th of such
year,  and shall  vest with  respect  to 1/12 of the  shares of Common  Stock so
granted  on the  15th  day of each  month  of such  calendar  year,  subject  to
forfeiture  of the then unvested  portion of such shares upon the  expiration of
the  term or  other  termination  of  this  Agreement  prior  to the end of such
calendar  year.  The  number of shares of Common  Stock to be  granted  shall be
determined  by  reference  to the fair  market  value of the Common  Stock as of
January  1st of the year in which such grant is made,  which  shall be (i) $4.25
per share of Common  Stock  for the  grant to be made with  respect  to the 1998
calendar  year and (ii) the Average  Closing  Price (as  defined  below) for any
subsequent calendar year during the term of this Agreement. For purposes of this
Agreement,  the "Average Closing Price" as of January 1st of any year shall mean
the average  closing price of the Company's  Common Stock reported on the Nasdaq
Stock  Market or any national  securities  exchange on which the Common Stock is
then  listed  during the period of 10  consecutive  trading  days ending one day
before such date. In addition, Company shall reimburse Consultant for reasonable
and necessary  expenses  which are incurred in connection  with his providing of
consulting  services and with respect to which Consultant  promptly  provides to
Company a detailed  expense  account,  provided  that any item of  expense  over
$1,500 has been approved by the Company in advance and in writing.

          3.3 Consultant  shall himself pay, and Company shall have no liability
for,  all  social  security,   federal  income  taxes,  unemployment  insurance,
workmen's compensation  insurance,  pensions,  annuities or other liabilities or
taxes incurred by or on behalf of or for the benefit of Consultant or any of his
agents, employees or servants who are not employed by the Company arising out of
the performance by Consultant of his obligations under this Agreement.

          4. Duty of  Faithfulness  owed by Consultant to Company During Term of
Agreement.

          4.1  During  the  term of this  Agreement  or any  extension  thereof,
Consultant  shall  faithfully  perform and provide the services  contemplated by
this Agreement for Company, and Consultant shall not perform the same or similar
services for any other entity.


<PAGE>

          4.2 In addition to the other  obligations  agreed to by  Consultant in
this  Agreement,  Consultant  agrees  that  following  the  termination  of this
Agreement he shall not at any time  directly or indirectly  (a) induce,  entice,
solicit any employee or  consultant of the Company to leave his  employment,  or
(b) contact, communicate or solicit any customer of the Company derived from any
customer list,  customer lead, mail, printed matter or information  secured from
the Company or its present or past employees, or (c) in any other manner use any
customer lists or customer leads, mail, telephone numbers,  printed materials or
material of the Company relating thereto.

          5. Disclosure and Ownership of Information.

          5.1 For the  purposes  of this  Agreement,  "Proprietary  Information"
shall mean all  information,  ideas,  concepts,  improvements,  discoveries  and
inventions  (including  those relating to research,  development,  financial and
sales data, pricing or trading terms,  evaluations,  opinions,  interpretations,
the identity of customers or of their requirements or of key contacts within the
customer's  organizations,  and marketing  and  merchandising  technique(s)  (i)
possessed,  acquired or developed by Company at any time,  irrespective of their
subject or nature, or (ii) conceived,  made, developed or acquired by Consultant
or disclosed or made known to Consultant,  individually  or jointly with others,
in  connection  with or as a  result  of  Consultant's  performance  under  this
Agreement that relate to the business, products or services of Company and/or to
the  Consulting  Subjects.  The term  "Proprietary  Information"  shall  include
without limitation all test data, documents,  memoranda,  notes, records, files,
correspondence,  drawings,  manuals, models,  specifications,  designs, computer
programs,  maps and all other writings or materials of any type embodying any of
such Proprietary Information.

          5.2 All Proprietary Information is and shall be the sole and exclusive
property of the Company.

          5.3 (a) During the term of this Agreement,  Consultant  shall promptly
disclose in writing to Company all Proprietary Information conceived, developed,
made or acquired by  Consultant,  either  individually  or jointly  with others,
whether patentable or not, and whether or not reduced to practice,  irrespective
of whether Consultant utilized Company's time, data,  facilities or material and
irrespective of whether such  Proprietary  Information is conceived,  developed,
discovered or acquired by Consultant on the job, at home, or elsewhere.

          (b) Consultant hereby specifically agrees to sell, assign and transfer
to Company or its nominee,  and by the execution of this  Agreement  does hereby
sell,  assign and  transfer  to Company or its  nominee,  all of his  world-wide
right, title and interest in and to all of the Proprietary Information described
in Section  5.3(a),  and any United States or foreign  applications  for patents
copyrights,  certificates of invention and other  industrial  rights that may be
filed  thereon,  including  divisions,  continuations,  continuations  in  part,
reissues  or  extension  thereon.  Both  during the term of this  Agreement  and
thereafter,  Consultant  agrees to at any time assist Company and/or its nominee
in the protection of such Proprietary  Information assigned herein to Company or
its nominee, both in the United States and foreign countries,  including but not
limited  to, the  execution  of all lawful  oaths and all  assignment  documents
requested by Company or its nominee in the  preparation,  prosecution,  issuance
and  enforcement  of any  applications  for United  States or  foreign  patents,
including  divisions,  continuations,  continuations in part, or reissued and/or
extensions  thereof,  of any  industrial  property  rights and  certificates  of
invention;  and/or any United States or foreign rights protecting proprietary or
confidential information.  If such assistance takes place after the term of this
Agreement has expired,  Consultant shall be paid by Company at a reasonable rate
(taking into  consideration  the services  performed  by  Consultant  as well as
Consultant's  normal  and  customary  rates)  for any  time  actually  spent  so
assisting Company or its nominee.
<PAGE>


          5.4  Consultant  recognizes  that the  protection  of the  Proprietary
Information of Company  against  unauthorized  disclosure and use is of critical
importance to Company,  and therefore  Consultant agrees to use his best efforts
and  exercise  utmost   diligence  to  protect  and  safeguard  the  Proprietary
Information  of  Company  and its  affiliates,  if any,  and,  except  as may be
expressly required by Company in connection with Consultant's performance of his
obligations to Company under this Agreement, Consultant shall not, either during
the term of this  Agreement or thereafter,  directly or indirectly,  use for his
own benefit or for the benefit of another,  or disclose to another,  any of such
Proprietary Information.

          5.5 Upon  termination  of this  Agreement,  or at any other  time upon
request, Consultant shall immediately deliver to Company all documents embodying
any of Company's Proprietary Information, including all test data.

          5.6 If during the term of this Agreement,  Consultant creates any work
of authorship  fixed in any tangible  medium of  expression  that is the subject
matter of copyright and that relates to Company's (or its  affiliate's,  if any)
business, products, or services, Company shall be deemed the author of such work
if the work is prepared by Consultant in the scope of his or her  consultancy by
virtue of the work  being a work made for hire or, if the work was not  prepared
by Consultant  within the scope of his or her employment or consultancy  but was
specially  ordered by Company as a contribution to a collective  work, as a part
of  a  motion  picture  or  other  audio-visual  work,  as a  translation,  as a
supplementary  work, as a compilation or as an instructional test, then the work
shall be  considered to be work made for hire and Company shall be the author of
the work.  With  regard to any other work of  authorship  fixed in any  tangible
medium of expression  that is the subject  matter of copyright and which relates
specifically  to the  business,  products  or  services of the Company or to the
Consulting  Subjects,  Consultant agrees to, and does hereby,  assign to Company
all worldwide  right,  title and interest in and to such works.  Both during the
term of this Agreement and thereafter,  Consultant  agrees to assist Company and
its nominee,  at any time, in the protection of Company's worldwide right, title
and interest in and to the work and all rights of copyright  therein,  including
but not limited to, the execution of all formal assignment  documents  requested
by Company or its nominee and the execution of all lawful oaths and applications
of registration of copyright in the United States and foreign countries.

          With regard to any work of  authorship  described  above,  the Company
agrees that it will consider and approve in its sole  discretion  such works for
publication  purposes  upon the request of  Consultant,  provided  that any such
publications  (i)  shall be  limited  to  scientific  publications,  (ii)  shall
identify clearly the relationship of Consultant to the Company,  and (iii) shall
not be  permitted if there would be, as a result of such  publication,  any risk
presented to potentially patentabl developments,  until steps have been taken to
protect such developments.

          5.7  Notwithstanding  anything in this Article 5 to the contrary,  the
Company  acknowledges  that Consultant is currently,  and will be throughout the
term of this  Agreement,  an employee of The  University  of Texas System Cancer
Center,  M. D.  Anderson  Hospital and Tumor  Institute  ("Anderson"),  and that
nothing  herein  shall  interfere  or  conflict  with  any  existing  employment
agreements or relationships between Consultant and Anderson. The Company further
acknowledges that the term "Proprietary Information",  as defined in Section 5.1
hereof and as used in this Article 5, shall not include any information,  ideas,
concepts,   improvements,   discoveries   and   inventions   which   Consultant,
individually or jointly,  conceives,  makes,  develops or acquires,  or which is
disclosed or made known to  Consultant,  while  Consultant  is working under the
Research and Development  Contract  between the Company and Anderson,  or on any
other sponsored research and development  agreement applicable to Anderson,  but
shall only apply to such information, ideas, concepts, improvements, discoveries
and inventions conceived, made, developed or required,  individually or jointly,
or made  known or  disclosed  to  Consultant,  while  Consultant  is  engaged in
performing services to Company under this Agreement.
<PAGE>

          6. Term and Termination.

          6.1 The initial term of this Agreement  (the "Initial  Term") shall be
for a period of three  years from the  effective  date of this  Agreement.  Upon
expiration  of  the  Initial  Term  (and  upon  expiration  of the  term  of any
subsequent extension), the term of this Agreement shall be automatically renewed
and extended for an additional one-year period,  unless one of the parties shall
give written notice to the other of its intention to terminate this Agreement at
least 30 days prior to the  expiration  of the  Initial  Term or any  subsequent
one-year  extension,  in  which  case  this  Agreement  shall  terminate  on the
expiration of the Initial Term or subsequent one-year extension, as the case may
be.

          6.2  Termination  of  this  Agreement   shall  not  affect   Company's
obligation to pay for services previously  performed by Consultant and shall not
affect Consultant's  continuing obligations to Company in Sections 3.3, 4.2, and
5.1  through  5.6  above,  whether  such  termination  is  made  voluntarily  or
involuntarily, by Company or Consultant, with or without cause.

          7. Terms Applicable to the Issuance of Common Stock.

          7.1 Unless the  offering,  sale and delivery of shares of Common Stock
issuable to  Consultant  pursuant to this  Agreement  have been  registered  and
continue to be so at the date of exercise  hereof  under the  Securities  Act of
1933 (the  "Act"),  Consultant  agrees  that the  shares of Common  Stock  which
Consultant  acquires thereby shall be acquired for investment  without a view to
distribution, within the meaning of the Act, and shall not be sold, transferred,
assigned,  pledged or hypothecated  in the absence of an effective  registration
statement  for the shares of Common  Stock  under the Act and  applicable  state
securities laws or an applicable exemption from the registration requirements of
the Act and any applicable state  securities  laws.  Consultant also agrees that
the shares of Common Stock which he may acquire  pursuant to this Agreement will
not be sold or disposed of in any manner  which would  constitute a violation of
any other  applicable  securities  laws,  whether federal or state. In addition,
Consultant  agrees (A) that the  certificates  representing the shares of Common
Stock issued under this Agreement may bear such legend or legends as the Company
deems appropriate in order to assure compliance with applicable securities laws,
and (B) that the Company may give  instruction to its transfer agent, if any, to
stop  transfer of the shares of Common Stock issued under this  Agreement on the
stock transfer  records of the Company,  if such proposed  transfer would in the
opinion of counsel  satisfactory  to the Company  constitute  a violation of any
applicable securities law or any such agreements.

          7.2 Consultant hereby represents and warrants that no provision in, or
activity  contemplated  by this  Agreement,  including  without  limitation  the
compensation  to be  received  by him  pursuant  to  Section  3.2,  violates  or
conflicts  with any  agreement,  regulation or policy by which he is bound or to
which he is subject,  whether related to his employment or otherwise,  except as
disclosed  on Exhibit A hereto and agreed to by the Company.  Consultant  agrees
that if any such violation or conflict  exists or arises in the future,  he will
be solely responsible for the satisfactory resolution thereof,  without recourse
to the  Company,  including  without  limitation  any  required  forfeitures  or
dispositions of compensation,  options or stocks.  Consultant agrees to disclose
to his employer the compensation  arrangements contained in this Agreement,  and
to provide  the  Company an  acknowledgment  thereof by such  employer  or other
evidence of such disclosure.
<PAGE>

          8. Miscellaneous.

          8.1 This  Agreement  shall inure to the benefit of and be binding upon
the respective heirs, executors,  successors,  representatives and assigns (and,
to the extent the last sentence of Section 2.1 applies, affiliates,  parents and
subsidiaries)  of the  parties,  as the  case  may be;  provided,  however,  the
obligations of each party herein to the other herein are personal and may not be
assigned without the express written consent of such other party.

          8.2 The laws of the State of Texas  will  govern  the  interpretation,
validity and effect of this  Agreement  without regard to the place of execution
or the place of performance thereof,  and the courts in Houston,  Harris County,
Texas shall have personal  jurisdiction  over Company and the Consultant to hear
all disputes  arising out of this  Agreement and venue shall be proper with such
courts to hear such  disputes.  In the event either Company or the Consultant is
not able to effect service of process upon the other in any  litigation  brought
in such courts with respect to such disputes, it is agreed that the Secretary of
State for the State of Texas shall be an agent of Company and the  Consultant to
receive service of process.

          8.3  Notices  or  payments  given by one party to the other  hereunder
shall be deemed to have been properly given or paid if deposited with the United
States Postal Service, registered or certified mail, addressed to the Consultant
at the address  listed below his  signature on the last page hereof,  and to the
Company at the following address, or in either case to such other address as the
party  receiving  notice shall have  designated  by written  notice to the other
party: Aronex Pharmaceuticals,  Inc. 8707 Technology Forest Place The Woodlands,
Texas 77381

          8.4 This Agreement  replaces all previous  agreements and  discussions
relating to the subject  matters  hereof and  constitutes  the entire  agreement
between  Company and  Consultant  with  respect to the  subject  matters of this
Agreement.  Without  limiting  the  foregoing,  this  Agreement  supersedes  and
terminates,  effective  January 1, 1998, the Consulting  Agreement dated July 1,
1988  between the Company and  Consultant,  as amended by the first,  second and
third amendments  thereto.  This Agreement may not be modified in any respect by
any verbal statement,  representation or agreement made by any employee, officer
or representative of Company,  or by any written document unless it is signed by
an officer of Company.

          8.5 If any term or  provision  of this  Agreement  is deemed  invalid,
contrary  to  or  prohibited   under  applicable  laws  or  regulations  of  any
jurisdiction, such provision shall be revised to the extent permitted by law and
the remaining provisions hereof shall not be invalidated.

          8.6 Both Consultant and Company  recognize that irreparable  injury or
damage  will  result to the  business of the other in the event of the breach of
any covenant  herein,  and each such party therefore agrees that in the event of
such breach by it, the other party shall be  entitled,  in addition to any legal
or equitable  remedies and damages  available,  to an injunction to restrain the
violation of this Agreement by the breaching  party and all other persons acting
for or on behalf of the breaching party.
<PAGE>


          IN WITNESS  WHEREOF,  the parties  have  executed  this  Agreement  in
duplicate originals effective the date first stated above.

                                              ARONEX PHARMACEUTICALS, INC. 


                                                               
Gabriel Lopez-Berestein                       Geoffrey Cox
                                              Chairman of the Board and
                                              Chief Executive Officer