REGISTRATION RIGHTS AGREEMENT

     THIS  REGISTRATION  RIGHTS  AGREEMENT,  dated as of  January  , 1997 by and
between Hemispherx Biopharma,  Inc., a Delaware corporation (the Company"),  and
the  person  whose  name  appears  on  the  signature   page   attached   hereto
(individually a "Holder" and collectively,  with the holders of other securities
issued in the Offering, the "Holders").

     WHEREAS,   pursuant  to  a  Subscription   Agreement   (the   "Subscription
Agreement"), the Holder has offered to purchase shares of the Company's Series E
Convertible Preferred Stock ("Series E Preferred Shares") from the Company;

     WHEREAS,  in order to induce the  Holders  to enter  into the  Subscription
Agreement  and to purchase  the Series E Preferred  Shares,  the Company and the
Holders have agreed to enter into this Agreement;

     WHEREAS,  it is intended by the Company and the Holders that his  Agreement
shall become  effective  immediately  upon the acquisition by the Holders of the
Series E Preferred Shares;

     NOW,  THEREFORE,  in consideration of the premises and the mutual covenants
contained herein, the Company hereby agrees as follows:

A. REGISTRATION RIGHTS

     1.   Registration Rights

          (a)  Option to  Include  Securities  in  Registration  Statement.  The
Company will use its best efforts to file a registration  statement  (subject to
the  availability  of the Company's  annual  Financial  Statements),  seeking to
register all shares of Common  Stock  underlying  the Series E Preferred  Shares
("Underlying Shares"), on Form S-1 or other comparable form, with the Securities
and Exchange  Commission  no later than 30 days from the closing of the Offering
(as  defined  in  the  accompanying   Agreement  between  the  Company  and  the
Holder)("Registration Statement"). The Company agrees to use its best efforts to
have the Registration Statement declared effective. The Holders agree to execute
and/or  deliver  such  documents in  connection  with such  registration  as the
Company may request.  If the Holders'  Underlying Shares are so registered,  the
Company's obligations under Article 1 herein will be deemed satisfied in full.

          (b)  Cooperation  with Company.  The Holders will  cooperate  with the
Company in all respects in connection  with this  Agreement,  including,  timely
supplying all information  reasonably requested by the Company and executing and
returning all documents reasonably requested in connection with the registration
and sale of the Underlying Shares.

     2. Registration Procedures.  If and whenever the Company is required by any
of the  provisions  of this  Agreement  to use its best  efforts  to effect  the
registration of any of the




Underlying  Shares under the  Securities  Act of 1933, as amended  ("Act"),  the
Company shall (except as otherwise provided in this Agreement), as expeditiously
as possible:

          (a) prepare and file with the Commission a Registration  Statement and
shall  use its best  efforts  to cause  such  Registration  Statement  to become
effective  and  remain  effective  until all the  Underlying  Shares are sold or
become capable of being publicly sold without registration under the Act.

          (b)  prepare  and  file  with  the  Commission   such  amendments  and
supplements to such Registration Statement and the prospectus used in connection
therewith as may be necessary to keep such Registration  Statement effective and
to  comply  with the  provisions  of the Act with  respect  to the sale or other
disposition of all securities  covered by such Registration  Statement  whenever
the Holder or  Holders  of such  securities  shall  desire to sell or  otherwise
dispose of the same (including prospectus  supplements with respect to the sales
of  securities  or the  exercise of the  Underlying  Shares from time to time in
connection  with  a  Registration   Statement   pursuant  to  Rule  415  of  the
Commission);

          (c) notify each Holder of Series E  Preferred  Shares  covered by such
Registration  Statement,  at any time when a prospectus relating thereto covered
by such Registration Statement is required to be delivered under the Act, of the
happening  of any  event of  which it has  knowledge  as a result  of which  the
prospectus included in such Registration  Statement, as then in effect, includes
any  untrue  statement  of a  material  fact or omits to state a  material  fact
required to be stated  therein or necessary to make the  statements  therein not
misleading in the light of the circumstances then existing; and

          (d) take such other  actions as shall be  reasonably  requested by any
Holder  to  facilitate  the  registration  and  sale of the  Underlying  Shares;
provided,  however,  that the Company shall not be obligated to take any actions
not specifically  required elsewhere herein which in the aggregate would cost in
excess of $5,000.

     3.  Expenses.  All expenses  incurred in any  registration  of the Holders'
Underlying Shares under this Agreement shall be paid by the Company,  including,
without limitation, printing expenses, fees and disbursements of counsel for the
Company  and each  participating  Holder,  expenses  of any  audits to which the
Company  shall agree or which  shall be  necessary  to comply with  governmental
requirements  in connection with any such  registration,  all  registration  and
filing  fees  for  the  Holders'  Underlying  Shares  under  federal  and  state
securities laws; provided,  however, the Company shall not be liable for (a) any
discounts or commissions  to any  underwriter  or  broker/dealer;  (b) any stock
transfer taxes incurred with respect to Underlying  Shares sold in the Offering;
or (c) the fees and  expenses  of  counsel  for any  Holder,  provided  that the
Company  will pay the costs and expenses of Company  counsel when the  Company's
counsel is representing any or all selling Holders.

     4.  Indemnification.  In the event any Underlying  Shares are included in a
Registration Statement pursuant to this Agreement:


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          (a)  Company  Indemnity.  Without  limitation  of any other  indemnity
provided to any Holder, either in connection with the Offering or otherwise,  to
the extent  permitted by law, the Company shall indemnify and hold harmless each
Holder,  the affiliates,  officers,  directors and partners of each Holder,  any
underwriter  (as defined in the Act) for such Holder,  and each person,  if any,
who controls  such Holder or  underwriter  (within the meaning of the Act or the
Securities  Exchange Act of 1934 ("Exchange Act"),  against any losses,  claims,
damages or liabilities (joint or several) to which they may become subject under
the Act, the Exchange Act or other federal or state law, insofar as such losses,
claims,  damages or liabilities (or actions in respect  thereof) arise out of or
are  based  upon  any of  the  following  statements,  omissions  or  violations
(collectively  a  "Violation"):  (i) any  untrue  statement  or  alleged  untrue
statement  of  a  material  fact  contained  in  such  Registration  Statements,
including any preliminary  prospectus or final prospectus  contained  therein or
any amendments or supplements thereto,  (ii) the omission or alleged omission to
state  therein a material fact  required to be stated  therein,  or necessary to
make the statements therein, in light of the circumstances under which they were
made, not misleading, (iii) any violation or alleged violation by the Company of
the Act or the  Exchange  Act, or (iv) any state  securities  law or any rule or
regulation  promulgated  under the Act, the Exchange Act or any state securities
law.  The  Company  shall  reimburse  each such  Holder,  affiliate,  officer or
director or partner,  underwriter or  controlling  person for any legal or other
expenses incurred by them in connection with investigating or defending any such
loss, claim, damage,  liability or action;  provided,  however, that the Company
shall  not be liable to any  Holder in any such case for any such  loss,  claim,
damage, liability or action to the extent that it arises out of or is based upon
a  Violation  which  occurs in  reliance  upon and in  conformity  with  written
information  furnished expressly for use in connection with such registration by
any such Holder or any other officer, director or controlling person thereof.

          (b) Holder  Indemnity.  Each Holder shall  indemnify and hold harmless
the Company, its affiliates, its counsel, officers, directors,  shareholders and
representatives,  any underwriter  (as defined in the Act),  against any losses,
claims,  damages,  or  liabilities  (joint or  several) to which they may become
subject  under  any  federal  or state  securities  law,  and the  Holder  shall
reimburse  the  Company,   its   affiliates,   counsel,   officers,   directors,
shareholders, representatives, underwriters or controlling persons for any legal
or other expenses incurred by them in connection with investigating or defending
any such loss,  claim,  damage,  liability  or action;  insofar as such  losses,
claims,  damages or liabilities (or actions in respect  thereof) arise out of or
are based upon any  statements  or  information  provided  by such Holder to the
Company in connection with the offer or sale of Underlying Shares.

          (c) Notice; Right to Defend.  Promptly after receipt by an indemnified
party under this ss.4, of notice of the  commencement  of any action  (including
any governmental  action),  such indemnified  party shall, if a claim in respect
thereof is to be made against any indemnifying party under this ss.4, deliver to
the  indemnifying  party a written  notice of the  commencement  thereof and the
indemnifying  party agrees that it will be responsible for any costs,  expenses,
judgments,  damages and losses incurred by the indemnified party with respect to
such claim,  jointly with any other indemnifying party similarly noticed, and to
assume the defense  thereof with counsel  mutually  satisfactory to the parties;
provided, however, that an indemnified party


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shall have the right to retain its own counsel, with the fees and expenses to be
paid by the indemnifying  party, if the indemnified  party  reasonably  believes
that  representation  of the  indemnified  party by the counsel  retained by the
indemnifying  party would be inappropriate due to actual or potential  differing
interests between such indemnified party and any other party represented by such
counsel  in such  proceeding.  The  failure  to  deliver  written  notice to the
indemnifying  party within a  reasonable  time of the  commencement  of any such
action shall relieve such indemnifying party of any liability to the indemnified
party  under  this  Agreement  only if and to the  extent  that such  failure is
prejudicial  to its ability to defend such  action,  and the omission to deliver
written  notice to the  indemnifying  party will not relieve it of any liability
that it may have to any indemnified party otherwise than under this Agreement.

          (d)  Contribution.   If  the  indemnification  provided  for  in  this
Agreement is held by a court of competent  jurisdiction  to be unavailable to an
indemnified party with respect to any loss, liability,  claim, damage or expense
referred to therein,  then the indemnifying  party, in lieu of indemnifying such
indemnified party thereunder,  shall contribute to the amount paid or payable by
such indemnified  party as a result of such loss,  liability,  claim,  damage or
expense in such  proportion as is  appropriate  to reflect the relative fault of
the indemnifying party on the one hand and of the indemnified party on the other
hand in connection with the statements or omissions which resulted in such loss,
liability,  claim,  damage or  expense as well as any other  relevant  equitable
considerations. The relevant fault of the indemnifying party and the indemnified
party shall be  determined  by  reference  to, among other  things,  whether the
untrue or alleged untrue statement of a material fact or the omission to state a
material fact relates to information  supplied by the  indemnifying  party or by
the indemnified  party and the parties'  relative intent,  knowledge,  access to
information  and  opportunity  to correct or prevent such statement or omission.
Notwithstanding  the  foregoing,  the amount any Holder  shall be  obligated  to
contribute  pursuant to the Agreement shall be limited to an amount equal to the
proceeds  to  such  Holder  of  the  Underlying  Shares  sold  pursuant  to  the
Registration  Statement which gives rise to such obligation to contribute  (less
the aggregate amount of any damages which the Holder has otherwise been required
to pay in  respect  of such  loss,  claim,  damage,  liability  or action or any
substantially similar loss, claim, damage,  liability or action arising from the
sale of such Underlying Shares).

          (e)  Survival  of  Indemnity.  The  indemnification  provided  by this
Agreement shall be a continuing right to  indemnification  and shall survive the
registration  and sale of any  registrable  securities by any person entitled to
indemnification hereunder and the expiration or termination of this Agreement.

     5. Assignment of Registration  Rights. The rights of the Holders under this
Agreement,  including  the rights to cause the  Company to  register  Underlying
Shares may not be assigned without the written prior consent of the Company.


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     6. Remedies.

          (a) Time is of Essence. The Company agrees that time is of the essence
for each of the covenants  contained  herein and that, in the event of a dispute
hereunder,  this Agreement is to be  interpreted  and construed in a manner that
will enable the Holders to sell their  Underlying  Shares as quickly as possible
after  such  Holders  have  indicated  to the  Company  that they  desire  their
Underlying  Shares to be  registered.  Any delay on the part of the  Company not
expressly  permitted  under this  Agreement,  whether  material or not, shall be
deemed a material breach of this Agreement.

          (b) Remedies Upon Default or Delay. The Company  acknowledges that the
breach of any part of this Agreement may cause  irreparable harm to a Holder and
that monetary damages alone may be inadequate. The Company therefore agrees that
the Holder  shall be  entitled  to  injunctive  relief or such other  applicable
remedy as a court of  competent  jurisdiction  may  provide.  Nothing  contained
herein  will be  construed  to limit a Holder's  right to any  remedies  at law,
including recovery of damages for breach of any part of this Agreement.

     7. Notices.

          (a) All  communications  under this Agreement  shall be in writing and
shall be mailed by first class mail, postage prepaid,  or telegraphed or telexed
with  confirmation  of receipt or  delivered  by hand or by  overnight  delivery
service,

               (i). If to the Company, at:

                    Hemispherx Biopharma, Inc.
                    1617 JFK Boulevard
                    Philadelphia, Pennsylvania 19103
                    Attn: Dr. William A. Carter

or at such other  address as it may have  furnished in writing to the Holders of
Series E Preferred Shares at the time outstanding, or

               (ii) if to any Holder of any Series E  Preferred  Shares,  to the
address  of such  Holder as it  appears  in the stock or  warrant  ledger of the
Company.

          (b) Any notice so  addressed,  when mailed by  registered or certified
mail shall be deemed to be given three days after so mailed, when telegraphed or
telexed shall be deemed to be given when transmitted,  or when delivered by hand
or overnight shall be deemed to be given when delivered.

     8. Successors and Assigns.  Except as otherwise  expressly provided herein,
this Agreement  shall inure to the benefit of and be binding upon the successors
and permitted assigns of the Company and each of the Holders.


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     9. Amendment and Waiver. This Agreement may be amended,  and the observance
of any term of this Agreement may be waived,  but only with the written  consent
of the  Company  and the Holders of  securities  representing  a majority of the
Series E Preferred Shares;  provided,  however, that no such amendment or waiver
shall  take away any  registration  right of any  Holder  of Series E  Preferred
Shares or reduce  the  amount of  reimbursable  costs to any  Holder of Series E
Preferred  Shares in  connection  with any  registration  hereunder  without the
consent of such Holder;  further provided,  however, that without the consent of
any other Holder of Series E Preferred Shares,  any Holder may from time to time
enter into one or more agreements amending,  modifying or waiving the provisions
of this  Agreement  if such  action  does not  adversely  affect  the  rights or
interest of any other Holder of Series E Preferred  Shares. No delay on the part
of any party in the exercise of any right,  power or remedy  shall  operate as a
waiver  thereof,  nor shall any single or partial  exercise  by any party of any
right,  power or remedy preclude any other or further exercise  thereof,  or the
exercise of any other right, power or remedy.

     10. Counterparts.  One or more counterparts of this Agreement may be signed
by the  parties,  each of which shall be an original  but all of which  together
shall constitute one and same instrument.

     11. Governing Law. This Agreement shall be construed in accordance with and
governed by the internal laws of the State of New York, without giving effect to
conflicts of law principles.

     12.  Invalidity of  Provisions.  If any  provision of this  Agreement is or
becomes  invalid,  illegal or  unenforceable  in any  respect,  the validity and
enforceability  of  the  remaining  provisions  contained  herein  shall  not be
affected thereby.


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     13.  Headings.  The  headings  in this  Agreement  are for  convenience  of
reference  only and  shall  not be deemed  to alter or  affect  the  meaning  or
interpretation of any provisions hereof.

     IN WITNESS  WHEREOF,  undersigned  have executed this Agreement as of the ,
day of January, 1997

                                        _______________________________
                                        Signature of Holder
HEMISPHERx BIOPHARMA, INC.


By: ___________________________         _______________________________
     Dr. William A. Carter,             Print Name of Holder
     President

                                        _______________________________

                                        _______________________________
                                        Print Address of Holder


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