FORM OF WARRANT

NEITHER THE ISSUANCE AND SALE OF THE SECURITIES  REPRESENTED BY THIS CERTIFICATE
NOR THE  SECURITIES  INTO  WHICH  THESE  SECURITIES  ARE  EXERCISABLE  HAVE BEEN
REGISTERED OR QUALIFIED  UNDER THE  SECURITIES  ACT OF 1933, AS AMENDED,  OR ANY
STATE SECURITIES LAWS. SUCH SECURITIES MAY NOT BE SOLD, TRANSFERRED OR OTHERWISE
DISPOSED  OF WITHOUT  EITHER (I) AN  EFFECTIVE  REGISTRATION  STATEMENT  FOR THE
SECURITIES  UNDER THE  SECURITIES  ACT OF 1933, AS AMENDED,  AND ANY  APPLICABLE
STATE  SECURITIES  LAWS, (II) AN OPINION OF COUNSEL,  IN A GENERALLY  ACCEPTABLE
FORM, THAT SUCH TRANSFER MAY BE MADE WITHOUT REGISTRATION OR QUALIFICATION UNDER
SAID ACT OR APPLICABLE  STATE  SECURITIES LAWS OR (III) SUCH TRANSFER BEING MADE
PURSUANT TO RULE 144 OR RULE 144A UNDER SAID ACT. NOTWITHSTANDING THE FOREGOING,
THIS WARRANT AND THE SECURITIES  INTO WHICH THIS WARRANT IS  EXERCISABLE  MAY BE
PLEDGED IN CONNECTION WITH A BONA FIDE MARGIN ACCOUNT OR OTHER LOAN OR FINANCING
ARRANGEMENT SECURED BY THE SECURITIES.

                               APHTON CORPORATION

                        WARRANT TO PURCHASE COMMON STOCK

Warrant No.:
            -------------
Number of Shares:
                 -------------
Date of Issuance: March 31, 2003 ("Issuance Date")


Aphton  Corporation,  a Delaware  corporation (the "Company"),  hereby certifies
that,  for Ten  United  States  Dollars  ($10.00)  and other  good and  valuable
consideration,  the receipt and sufficiency of which are hereby acknowledged,  ,
the registered holder hereof or its permitted assigns,  is entitled,  subject to
the terms set forth below,  to purchase from the Company,  at the Exercise Price
(as defined  below) then in effect,  upon  surrender of this Warrant to Purchase
Common  Stock  (including  all  Warrants  to  Purchase  Common  Stock  issued in
exchange,  transfer or replacement hereof, the "Warrant"),  at any time or times
on or after the date on which the Company obtains the  Stockholder  Approval (as
defined in the Securities Purchase Agreement (as defined below)),  but not after
11:59  P.M.,  New  York  Time,  on  the  Expiration  Date  (as  defined  below),
______________  (_____________)  fully paid nonassessable shares of Common Stock
(as defined below) (the "Warrant Shares"). Except as

<PAGE>

otherwise  defined  herein,  capitalized  terms in this  Warrant  shall have the
meanings  set forth in  Section  15.  This  Warrant  is one of the  Warrants  to
Purchase Common Stock (the "SPA Warrants")  issued pursuant to Section 1 of that
certain Securities Purchase Agreement,  dated as of March 31, 2003 (the "Initial
Issuance  Date"),  among  the  Company  and the  purchasers  (the  "Purchasers")
referred to therein (the "Securities Purchase Agreement").


     1.   EXERCISE OF WARRANT.

          (a) Mechanics of Exercise.  Subject to the terms and conditions hereof
(including, without limitation, the limitations set forth in Section 1(f)), this
Warrant may be exercised by the holder hereof on any day from and after the date
on which the Company obtains the Stockholder  Approval,  in whole or in part, by
(i) delivery of a written notice,  in the form attached hereto as Exhibit A (the
"Exercise Notice"), of such holder's election to exercise this Warrant, (ii) (A)
payment  to the  Company of an amount  equal to the  applicable  Exercise  Price
multiplied  by the  number of Warrant  Shares as to which this  Warrant is being
exercised  (the  "Aggregate  Exercise  Price")  in cash or by wire  transfer  of
immediately available funds or (B) by notifying the Company that this Warrant is
being exercised pursuant to a Cashless Exercise (as defined in Section 1(d)) and
(iii) the surrender to a common  carrier for overnight  delivery to the Company,
on or as soon as  practicable  following  the date the  holder  of this  Warrant
delivers  the  Exercise   Notice  to  the  Company,   of  this  Warrant  (or  an
indemnification  undertaking  with  respect  to this  Warrant in the case of its
loss, theft or  destruction).  On or before the third Business Day following the
date on  which  the  Company  has  received  each of the  Exercise  Notice,  the
Aggregate Exercise Price (or notice of a Cashless Exercise) and this Warrant (or
an  indemnification  undertaking with respect to this Warrant in the case of its
loss, theft or destruction)  (the "Exercise  Delivery  Documents"),  the Company
shall (X) issue and deliver to the address  specified in the Exercise  Notice, a
certificate,  registered  in the  name  of the  holder  of this  Warrant  or its
designee,  for the number of shares of Common  Stock to which the holder of this
Warrant  is  entitled  pursuant  to such  exercise,  or (Y)  provided  that  the
Company's  transfer  agent  (the  "Transfer  Agent")  is  participating  in  The
Depository  Trust Company ("DTC") Fast Automated  Securities  Transfer  Program,
upon the request of the holder, credit such aggregate number of shares of Common
Stock to which the holder of this Warrant is entitled  pursuant to such exercise
to the holder's or its designee's  balance  account with DTC through its Deposit
Withdrawal  Agent  Commission  system.  Upon delivery of the Exercise Notice and
Aggregate  Exercise Price referred to in clause (ii)(A) above or notification to
the Company of a Cashless  Exercise  referred to in Section 1(d),  the holder of
this  Warrant  shall be deemed for all  corporate  purposes  to have  become the
holder of record of the Warrant  Shares with  respect to which this  Warrant has
been exercised, irrespective of the date of delivery of this Warrant as required
by clause (iii) above or the certificates evidencing such Warrant Shares. If the
number of Warrant  Shares  represented  by this Warrant  submitted  for exercise
pursuant to this Section 1(a) is greater than the number of Warrant Shares being
acquired upon an exercise,  then the Company shall as soon as practicable and in
no event  later  than three  Business  Days  after any  exercise  and at its own
expense,  issue a new Warrant (in accordance with Section 7(d)) representing the
right to purchase the number of Warrant Shares purchasable  immediately prior to
such exercise under this Warrant, less the number of Warrant Shares with respect
to which this Warrant is exercised.  No fractional shares of Common Stock are to
be issued upon the exercise of this Warrant,  but

                                       -2-
<PAGE>

rather the number of shares of Common  Stock to be issued shall be rounded up to
the nearest whole  number.  The Company shall pay any and all taxes which may be
payable  with  respect to the  issuance  and  delivery  of Warrant  Shares  upon
exercise of this Warrant.

          (b) Exercise  Price.  For purposes of this Warrant,  "Exercise  Price"
means $2.70, subject to adjustment as provided herein.

          (c) Company's Failure to Timely Deliver Securities.

     (i)  Failure to Deliver  Shares.  Subject to Section  1(f),  if the Company
     shall fail for any reason or for no reason to issue to the  holder,  within
     three  Business  Days of  receipt of the  Exercise  Delivery  Documents,  a
     certificate for the number of shares of Common Stock to which the holder is
     entitled or to credit the holder's balance account with DTC for such number
     of shares of Common Stock to which the holder is entitled upon the holder's
     exercise of this Warrant,  the Company  shall pay as additional  damages in
     cash to such  holder on each day after  such  third  Business  Day that the
     issuance of such Common Stock  certificate is not timely effected an amount
     equal to 1.0% of the  product  of (A) the sum of the  number  of  shares of
     Common  Stock not issued to the  holder on a timely  basis and to which the
     holder is entitled  and (B) the Closing  Sale Price of the Common  Stock on
     the trading day  immediately  preceding  the last  possible  date which the
     Company could have issued such Common Stock to the holder without violating
     Section 1(a). In addition,  the holder, upon written notice to the Company,
     may void its  Exercise  Notice  with  respect  to, and have  returned,  any
     portion  of this  Warrant  that has not  been  exercised  pursuant  to such
     Exercise Notice;  provided that the voiding of an Exercise Notice shall not
     affect the Company's  obligations  to make any payments  which have accrued
     prior  to the date of such  notice  pursuant  to this  Section  1(c)(i)  or
     otherwise.

     (ii) Failure to Deliver New Warrant.  If within ten Business Days after the
     Company's receipt of the Exercise Delivery Documents,  the Company fails to
     deliver a new  Warrant  to the  holder  for the  number of shares of Common
     Stock to which such holder is entitled, the Company shall pay as additional
     damages in cash to such  holder on each day after such tenth  Business  Day
     that such  delivery  of such new  Warrant is not timely  effected an amount
     equal to 1.0% of the  product of (A) the  number of shares of Common  Stock
     represented by the portion of this Warrant which is not being exercised and
     (B)  the  Closing  Sale  Price  of the  Common  Stock  on the  trading  day
     immediately  preceding  the last possible date which the Company could have
     issued such Warrant to the holder without violating Section 1(a).

          (d) Cashless  Exercise.  Notwithstanding  anything contained herein to
the contrary,  the holder of this Warrant may, in its sole discretion,  exercise
this  Warrant  in whole  or in part  and,  in lieu of  making  the cash  payment
otherwise  contemplated  to be made to the Company upon such exercise in payment
of the Aggregate Exercise Price, elect instead to

                                       -3-

<PAGE>

receive upon such exercise the "Net Number" of shares of Common Stock determined
according to the following formula (a "Cashless Exercise"):

         Net Number = (A x B) - (A x C)
                      -----------------
                              B
                  For purposes of the foregoing formula:

                           A= the total number of shares with respect to which
                           this Warrant is then being exercised.

                           B= the Closing Sale Price of the Common Stock (as
                           reported by Bloomberg) on the date immediately
                           preceding the date of the Exercise Notice.

                           C= the Exercise Price then in effect for the
                           applicable Warrant Shares at the time of such
                           exercise.

          (e) Disputes.  In the case of a dispute as to the determination of the
Exercise Price or the arithmetic  calculation of the Warrant Shares, the Company
shall  promptly  issue to the holder the number of Warrant  Shares  that are not
disputed and resolve such dispute in accordance with Section 12.

          (f) Limitations on Exercises.

     (i) Beneficial Ownership. The Company shall not effect the exercise of this
     Warrant,  and no Person (as defined  below) who is a holder of this Warrant
     shall have the right to  exercise  this  Warrant,  to the extent that after
     giving effect to such  exercise,  such Person  (together with such Person's
     affiliates) would  beneficially own in excess of [4.99%](1)  [19.99%](2) of
     the shares of the Common Stock outstanding  immediately after giving effect
     to such  exercise.  For purposes of the foregoing  sentence,  the aggregate
     number of shares of Common Stock  beneficially owned by such Person and its
     affiliates shall include the number of shares of Common Stock issuable upon
     exercise of this Warrant with  respect to which the  determination  of such
     sentence  is being made,  but shall  exclude  shares of Common  Stock which
     would be issuable upon (i) exercise of the remaining,  unexercised  portion
     of this Warrant  beneficially  owned by such Person and its  affiliates and
     (ii) exercise or conversion of the  unexercised or  unconverted  portion of
     any other securities of the Company  beneficially  owned by such Person and
     its affiliates  (including,  without  limitation,  any convertible notes or
     convertible  preferred  stock  or  warrants)  subject  to a  limitation  on
     conversion or exercise analogous to the limitation contained herein. Except
     as set forth in the  preceding  sentence,  for purposes of this  paragraph,
     beneficial  ownership  shall be calculated in accordance with Section 13(d)
     of the  Securities  Exchange Act of 1934, as amended.  For purposes of this
     Warrant,  in determining the number of outstanding shares of Common Stock a
     holder may rely on the


------------------
1  For SF Capital.
2  For Heartland and Citigroup.

                                      -4-

<PAGE>

     number  of  outstanding  shares  of Common  Stock as  reflected  in (1) the
     Company's most recent Form 10-Q,  Form 10-K or other public filing with the
     Securities and Exchange  Commission,  as the case may be, (2) a more recent
     public  announcement  by the Company or (3) any other notice by the Company
     or its Transfer  Agent  setting  forth the number of shares of Common Stock
     outstanding.  For any reason at any time,  upon the written or oral request
     of the holder of this  Warrant,  the Company shall within one Business Days
     confirm  orally and in writing to the holder of this  Warrant the number of
     shares  of Common  Stock  then  outstanding.  In any  case,  the  number of
     outstanding  shares of Common Stock shall be determined after giving effect
     to the  conversion or exercise of securities of the Company,  including the
     SPA Securities and the SPA Warrants,  by the holder of this Warrant and its
     affiliates since the date as of which such number of outstanding  shares of
     Common Stock was reported.

     (ii)  Principal  Market  Regulation.  The Company shall not be obligated to
     issue any  shares of Common  Stock  upon  exercise  of this  Warrant if the
     issuance of such shares of Common  Stock would exceed that number of shares
     of Common  Stock which the Company may issue upon  exercise of this Warrant
     (including,  as  applicable,   any  shares  of  Common  Stock  issued  upon
     conversion  of or as  payment  of any  interest  under the SPA  Securities)
     without breaching the Company's  obligations under the rules or regulations
     of the Principal Market (the "Exchange  Cap"),  except that such limitation
     shall not apply in the event that the Company  obtains the  approval of its
     shareholders  as required by the applicable  rules of the Principal  Market
     for issuances of Common Stock in excess of such amount. Until such approval
     is  obtained,  no  Purchaser  shall be  issued,  upon  exercise  of any SPA
     Warrants, shares of Common Stock.

     (iii) Stockholder Approval. The Company shall not be obligated to issue any
     shares of  Common  Stock  upon  exercise  of this  Warrant  if  Stockholder
     Approval has not been obtained.

     2. ADJUSTMENT OF EXERCISE PRICE AND NUMBER OF WARRANT SHARES.  The Exercise
Price and the number of Warrant  Shares  shall be adjusted  from time to time as
follows:

          (a)  Adjustment  upon Issuance of Common Stock.  If and whenever on or
prior to the thirty-six (36) month anniversary of the Initial Issuance Date, the
Company issues or sells,  or in accordance with this Section 2 is deemed to have
issued or sold,  any shares of Common Stock  (including  the issuance or sale of
shares of Common Stock owned or held by or for the account of the  Company,  but
excluding  shares of Common  Stock deemed to have been issued by the Company (I)
in  connection  with any employee  benefit  plan which has been  approved by the
Board of Directors of the Company,  pursuant to which the  Company's  securities
may be issued to any employee,  officer or director for services provided to the
Company (an "Approved  Stock Plan"),  (II) upon conversion of any SPA Securities
or upon  exercise of any SPA Warrants,  (III) in connection  with the payment of
any  interest  in  shares  of  Common  Stock  on any SPA  Securities  or (IV) in
connection with any Excluded Security ((I) through (IV) collectively,  "Excluded
Issuances"))  for a consideration  per share ("New  Securities  Issuance Price")
less than a price (the "Applicable Price") equal to the Exercise Price in effect
immediately  prior  to

                                      -5-
<PAGE>

such  issue or sale or  deemed  issuance  or sale  (the  foregoing  a  "Dilutive
Issuance"), then immediately after such issue or sale or deemed issuance or sale
the Exercise Price then in effect shall be reduced to an amount equal to the New
Securities Issuance Price; provided, however, that if any such Dilutive Issuance
occurs after the twelve (12) month  anniversary of the Initial Issuance Date and
prior to the thirty-six  (36) month  anniversary  of the Initial  Issuance Date,
then the  Exercise  Price shall not be adjusted  pursuant to this  Section  2(a)
below a price equal to 80% of the Applicable  Price. If and whenever on or after
the thirty-six (36) month  anniversary of the Initial Issuance Date and prior to
the Expiration Date, the Company issues or sells, or is deemed to have issued or
sold,  any shares of Common Stock  (including  the issuance or sale of shares of
Common Stock owned or held by or for the account of the Company,  but  excluding
shares of Common  Stock  issued or deemed to be issued  pursuant to any Excluded
Issuance) in a Dilutive  Issuance,  then  concurrent  with such issue or sale or
deemed issuance or sale, the Exercise Price then in effect shall be reduced to a
price  (rounded  to the nearest  cent) equal to the product of (x) the  Exercise
Price in effect  immediately prior to such issuance or sale and (y) the quotient
determined by dividing (1) the sum of (I) the product derived by multiplying the
Exercise  Price in effect  immediately  prior to such  Dilutive  Issuance by the
number of shares of Common Stock Deemed  Outstanding  immediately  prior to such
issue or sale, plus (II) the consideration, if any, received by the Company upon
such Dilutive  Issuance,  by (2) the product  derived by multiplying the (I) the
Exercise Price in effect immediately prior to such Dilutive Issuance by (II) the
number of shares of Common  Stock  Deemed  Outstanding  immediately  after  such
Dilutive  Issuance.  Upon each such adjustment of the Exercise Price  hereunder,
the number of Warrant Shares shall be adjusted to the number of shares of Common
Stock determined by multiplying the Exercise Price in effect  immediately  prior
to such  adjustment by the number of Warrant Shares  acquirable upon exercise of
this  Warrant  immediately  prior to such  adjustment  and  dividing the product
thereof by the Exercise Price  resulting from such  adjustment.  For purposes of
determining  the adjusted  Exercise Price under this Section 2(a), the following
shall be applicable:

     (i) Issuance of Options. If at any time after the Initial Issuance Date the
     Company in any manner grants any Options and the lowest price per share for
     which one share of Common  Stock is issuable  upon the exercise of any such
     Option  or  upon  conversion,  exercise  or  exchange  of  any  Convertible
     Securities  issuable  upon  exercise  of any such  Option  is less than the
     Applicable  Price,  then such share of Common  Stock  shall be deemed to be
     outstanding  and to have been issued and sold by the Company at the time of
     the granting or sale of such Option for such price per share.  For purposes
     of this Section 2(a)(i), the "lowest price per share for which one share of
     Common Stock is issuable upon exercise of such Options or upon  conversion,
     exercise or exchange of such Convertible  Securities" shall be equal to the
     sum of the lowest amounts of consideration  (if any) received or receivable
     by the  Company  with  respect  to any one share of Common  Stock  upon the
     granting  or sale of the  Option,  upon  exercise  of the  Option  and upon
     conversion,  exercise or exchange of any Convertible Security issuable upon
     exercise of such Option.  No further  adjustment  of the Exercise  Price or
     number of Warrant  Shares  shall be made upon the actual  issuance  of such
     Common Stock or of such  Convertible  Securities  upon the exercise of such
     Options or upon the actual  issuance of such Common Stock upon  conversion,
     exercise or exchange of such Convertible Securities.

                                      -6-

<PAGE>

     (ii) Issuance of Convertible  Securities.  If at any time after the Initial
     Issuance  Date the  Company in any manner  issues or sells any  Convertible
     Securities  and the  lowest  price  per share for which one share of Common
     Stock is issuable upon the conversion, exercise or exchange thereof is less
     than the Applicable  Price, then such share of Common Stock shall be deemed
     to be  outstanding  and to have been  issued and sold by the Company at the
     time of the issuance or sale of such Convertible  Securities for such price
     per share. For the purposes of this Section 2(a)(ii), the "lowest price per
     share for which one share of Common Stock is issuable upon the  conversion,
     exercise or  exchange"  shall be equal to the sum of the lowest  amounts of
     consideration  (if any)  received or receivable by the Company with respect
     to one share of Common Stock upon the  issuance or sale of the  Convertible
     Security  and upon  conversion,  exercise or  exchange of such  Convertible
     Security.  No further adjustment of the Exercise Price or number of Warrant
     Shares  shall be made upon the actual  issuance of such  Common  Stock upon
     conversion, exercise or exchange of such Convertible Securities, and if any
     such issue or sale of such Convertible  Securities is made upon exercise of
     any Options for which  adjustment of this Warrant has been or is to be made
     pursuant to other provisions of this Section 2(a), no further adjustment of
     the Exercise  Price or number of Warrant  Shares shall be made by reason of
     such issue or sale.

     (iii) Change in Option Price or Rate of  Conversion.  If the purchase price
     provided for in any Options  issued after the Initial  Issuance  Date,  the
     additional  consideration,  if any,  payable  upon the  issue,  conversion,
     exercise or exchange of any Convertible Securities issued after the Initial
     Issuance Date, or the rate at which any Convertible Securities issued after
     the date hereof are  convertible  into or exercisable or  exchangeable  for
     Common Stock increases or decreases at any time, the Exercise Price and the
     number of Warrant Shares in effect at the time of such increase or decrease
     shall be adjusted to the  Exercise  Price and the number of Warrant  Shares
     which  would  have  been in  effect  at  such  time  had  such  Options  or
     Convertible  Securities  provided for such increased or decreased  purchase
     price, additional  consideration or increased or decreased conversion rate,
     as the case may be, at the time  initially  granted,  issued  or sold.  For
     purposes  of  this  Section  2(a)(iii),  if  the  terms  of any  Option  or
     Convertible  Security  that was  outstanding  as of the date of issuance of
     this Warrant are  increased  or  decreased  in the manner  described in the
     immediately  preceding sentence,  then such Option or Convertible  Security
     and the Common Stock deemed issuable upon exercise,  conversion or exchange
     thereof shall be deemed to have been issued as of the date of such increase
     or decrease.  No adjustment  pursuant to this Section 2(a) shall be made if
     such  adjustment  would result in an increase of the Exercise Price then in
     effect or a decrease in the number of Warrant Shares.

     (iv) Calculation of Consideration Received. In case any Option is issued in
     connection  with  the  issue or sale of other  securities  of the  Company,
     together  comprising  one  integrated  transaction  in  which  no  specific
     consideration  is  allocated to such  Options by the parties  thereto,  the
     Options will be deemed to have been issued for a consideration of $0.01. If
     any Common Stock,  Options or Convertible  Securities are issued or sold or
     deemed to have been  issued or sold for cash,  the  consideration  received
     therefor  will be  deemed  to be the net  amount  received  by the  Company
     therefor. If any Common Stock,

                                      -7-
<PAGE>

     Options or Convertible  Securities  are issued or sold for a  consideration
     other than cash, the amount of such  consideration  received by the Company
     will  be  the  fair  value  of  such   consideration,   except  where  such
     consideration  consists  of  securities,   in  which  case  the  amount  of
     consideration  received  by the Company  will be the Closing  Sale Price of
     such  security  on the date of  receipt.  If any Common  Stock,  Options or
     Convertible Securities are issued to the owners of the non-surviving entity
     in connection with any merger in which the Company is the surviving entity,
     the amount of consideration therefor will be deemed to be the fair value of
     such portion of the net assets and business of the non-surviving  entity as
     is attributable to such Common Stock, Options or Convertible Securities, as
     the case may be.  The fair  value of any  consideration  other than cash or
     securities will be determined jointly by the Company and the holders of SPA
     Warrants  representing  at least  two-thirds  of the shares of Common Stock
     obtainable  upon  exercise of the SPA Warrants  then  outstanding.  If such
     parties are unable to reach  agreement  within 10 days after the occurrence
     of an event requiring valuation (the "Valuation Event"),  the fair value of
     such  consideration  will be determined  within fifteen Business Days after
     the tenth day following the Valuation  Event by an  independent,  reputable
     appraiser  jointly  selected by the Company and the holders of SPA Warrants
     representing at least  two-thirds of the shares of Common Stock  obtainable
     upon exercise of the SPA Warrants then  outstanding.  The  determination of
     such appraiser  shall be final and binding upon all parties absent manifest
     error and the fees and  expenses  of such  appraiser  shall be borne by the
     Company.

     (v) Record  Date.  If the  Company  takes a record of the holders of Common
     Stock for the purpose of entitling  them (A) to receive a dividend or other
     distribution payable in Common Stock, Options or in Convertible  Securities
     or (B) to subscribe for or purchase  Common Stock,  Options or  Convertible
     Securities,  then  such  record  date  will be deemed to be the date of the
     issue or sale of the shares of Common  Stock  deemed to have been issued or
     sold upon the  declaration  of such  dividend  or the  making of such other
     distribution  or the date of the granting of such right of  subscription or
     purchase, as the case may be.

     (vi) Aventis  Debentures.  If the Company  causes the  conversion of all or
     part of the  Aventis  Debentures  (as  defined in the  Securities  Purchase
     Agreement) (each, an "Aventis  Conversion") at a conversion price per share
     of Common Stock the ("Aventis  Conversion Price") that is less than a price
     equal to the  Exercise  Price in effect  immediately  prior to such Aventis
     Conversion,  then immediately after such Aventis  Conversion,  the Exercise
     Price then in effect  shall be reduced  to an amount  equal to the  Aventis
     Conversion Price.

     [Insert in Additional Warrants only: (vii) This Warrant Deemed Outstanding.
     If during the period  beginning on and including the Initial  Issuance Date
     and ending on the date  immediately  preceding the date of issuance of this
     Warrant, the Company entered into, or in accordance with Section 2(a) would
     have been deemed to have entered into (had this Warrant been outstanding at
     such time), any Dilutive Issuance,  then solely for purposes of determining
     any adjustment  under this Section 2 as a result of such Dilutive

                                      -8-
<PAGE>

     Issuance or deemed Dilutive Issuance,  this Warrant shall be deemed to have
     been  outstanding  at the time of each  such  Dilutive  Issuance  or deemed
     Dilutive Issuance.]

          (b) Adjustment upon Subdivision or Combination of Common Stock. If the
Company at any time after the date of issuance of this  Warrant  subdivides  (by
any stock split,  stock  dividend,  recapitalization  or otherwise)  one or more
classes  of its  outstanding  shares of Common  Stock  into a greater  number of
shares,  the Exercise Price in effect immediately prior to such subdivision will
be   proportionately   reduced  and  the  number  of  Warrant   Shares  will  be
proportionately increased. If the Company at any time after the date of issuance
of this Warrant combines (by combination,  reverse stock split or otherwise) one
or more classes of its outstanding  shares of Common Stock into a smaller number
of shares,  the Exercise Price in effect  immediately  prior to such combination
will be  proportionately  increased  and the  number of Warrant  Shares  will be
proportionately  decreased.  Any adjustment under this Section 2(b) shall become
effective at the close of business on the date the  subdivision  or  combination
becomes effective.

          (c) Other Events.  If any event occurs of the type contemplated by the
provisions of this Section 2 but not expressly  provided for by such  provisions
(including,  without  limitation,  the  granting of stock  appreciation  rights,
phantom stock rights or other rights with equity  features),  then the Company's
Board of Directors will make an appropriate adjustment in the Exercise Price and
the number of Warrant  Shares so as to protect  the rights of the holder of this
Warrant in accordance  with the essential  intent and principles of this Section
2; provided that no such adjustment  pursuant to this Section 2(c) will increase
the  Exercise  Price or  decrease  the  number of  Warrant  Shares as  otherwise
determined pursuant to this Section 2.

     3. RIGHTS UPON DISTRIBUTION OF ASSETS. If the Company shall declare or make
any  dividend  or other  distribution  of its assets  (or rights to acquire  its
assets)  to holders of Common  Stock,  by way of return of capital or  otherwise
(including,  without  limitation,  any  distribution  of  cash,  stock  or other
securities,   property   or   options   by  way  of  a   dividend,   spin   off,
reclassification,  corporate  rearrangement  or other  similar  transaction)  (a
"Distribution"),  at any time after the issuance of this Warrant,  then, in each
such case:

          (a) any  Exercise  Price in effect  immediately  prior to the close of
business  on the record  date fixed for the  determination  of holders of Common
Stock entitled to receive the Distribution shall be reduced, effective as of the
close of business on such record date, to a price determined by multiplying such
Exercise Price by a fraction of which (i) the numerator shall be the Closing Bid
Price of the Common Stock on the trading day  immediately  preceding such record
date minus the value of the  Distribution  (as  determined  in good faith by the
Company's Board of Directors)  applicable to one share of Common Stock, and (ii)
the  denominator  shall be the  Closing  Bid  Price of the  Common  Stock on the
trading day immediately preceding such record date; and

          (b) the number of Warrant  Shares  shall be  increased  to a number of
shares  equal to the  number of shares of Common  Stock  obtainable  immediately
prior to the close of business on the record date fixed for the determination of
holders of Common Stock entitled to receive the  Distribution  multiplied by the
reciprocal of the fraction set forth in the immediately

                                      -9-
<PAGE>

preceding  paragraph (a); provided that in the event that the Distribution is of
common stock ("Other Common Stock") of a company whose common stock is traded on
a national  securities  exchange or a national automated  quotation system, then
the holder of this  Warrant  may elect to receive a warrant  to  purchase  Other
Common Stock in lieu of an increase in the number of Warrant  Shares,  the terms
of which shall be identical to those of this  Warrant,  except that such warrant
shall be exercisable  into the number of shares of Other Common Stock that would
have been payable to the holder of this Warrant pursuant to the Distribution had
the holder exercised this Warrant immediately prior to such record date and with
an  aggregate  exercise  price  equal to the  product of the amount by which the
exercise  price of this Warrant was decreased  with respect to the  Distribution
pursuant to the terms of the immediately  preceding paragraph (a) and the number
of Warrant Shares calculated in accordance with the first part of this paragraph
(b).

     4. PURCHASE RIGHTS; ORGANIC CHANGE.

          (a)  Purchase  Rights.  In  addition  to any  adjustments  pursuant to
Section 2 above, if at any time the Company grants, issues or sells any Options,
Convertible  Securities  or rights to purchase  stock,  warrants,  securities or
other  property pro rata to the record holders of any class of Common Stock (the
"Purchase Rights"), then the holder of this Warrant will be entitled to acquire,
upon the terms applicable to such Purchase Rights, the aggregate Purchase Rights
which such  holder  could have  acquired  if such  holder had held the number of
shares of  Common  Stock  acquirable  upon  complete  exercise  of this  Warrant
(without regard to any limitations on the exercise of this Warrant)  immediately
before  the date on which a record is taken for the grant,  issuance  or sale of
such Purchase  Rights,  or, if no such record is taken, the date as of which the
record holders of Common Stock are to be determined for the grant, issue or sale
of such Purchase Rights.

          (b)   Organic   Change.    Any    recapitalization,    reorganization,
reclassification, consolidation, merger, sale of all or substantially all of the
Company's assets to another Person or other  transaction,  in each case which is
effected  in such a way that  holders of Common  Stock are  entitled  to receive
securities or assets with respect to or in exchange for Common Stock is referred
to herein as an  "Organic  Change."  Subject to Section  4(n) of the  Securities
Purchase  Agreement,  prior  to the  consummation  of  any  (i)  sale  of all or
substantially  all of the Company's  assets to an acquiring Person or (ii) other
Organic  Change  following  which the  Company is not a  surviving  entity,  the
Company will secure from the Person purchasing such assets or the Person issuing
the securities or providing the assets in such Organic Change (in each case, the
"Acquiring  Entity")  a  written  agreement  (in form and  substance  reasonably
satisfactory to the holders of SPA Warrants  representing at least two-thirds of
the shares of Common Stock  obtainable  upon  exercise of the SPA Warrants  then
outstanding)  to  deliver to the holder of this  Warrant  in  exchange  for this
Warrant,  a security of the Acquiring Entity  evidenced by a written  instrument
substantially  similar in form and  substance  to this  Warrant  and  reasonably
satisfactory  to the holder of this  Warrant  (including,  an adjusted  exercise
price  equal to the value for the Common  Stock  reflected  by the terms of such
consolidation,  merger or sale, and exercisable  for a  corresponding  number of
shares of Common Stock  acquirable and receivable  upon exercise of this Warrant
(without  regard to any  limitations  on the exercise of this  Warrant),  if the
value so reflected is less than the Exercise Price in effect  immediately  prior
to such consolidation, merger or sale). In the event that an Acquiring Entity is
directly or  indirectly

                                      -10-
<PAGE>

controlled by a company or entity whose common stock or similar equity  interest
is listed,  designated or quoted on a securities exchange or trading market, the
holder of this  Warrant may elect to treat such Person as the  Acquiring  Entity
for  purposes  of this  Section  4(b).  Prior to the  consummation  of any other
Organic  Change,  the  Company  shall make  appropriate  provision  (in form and
substance reasonably satisfactory to the holders of SPA Warrants representing at
least  two-thirds of the shares of Common Stock  obtainable upon exercise of the
SPA  Warrants  then  outstanding)  to insure  that the  holder  of this  Warrant
thereafter  will have the right to acquire and receive in lieu of or in addition
to (as the case may be) the  shares  of  Common  Stock  immediately  theretofore
acquirable and receivable  upon the exercise of this Warrant  (without regard to
any  limitations  on the  exercise  of this  Warrant),  such  shares  of  stock,
securities  or assets  that  would have been  issued or payable in such  Organic
Change with  respect to or in exchange  for the number of shares of Common Stock
which  would have been  acquirable  and  receivable  upon the  exercise  of this
Warrant as of the date of such Organic Change (without regard to any limitations
on the exercise of this Warrant).

     5.  NONCIRCUMVENTION.  The  Company  hereby  covenants  and agrees that the
Company will not, by amendment of its  Certificate of  Incorporation  or through
any  reorganization,  transfer of assets,  consolidation,  merger,  dissolution,
issue or sale of securities,  or any other  voluntary  action,  avoid or seek to
avoid the  observance or  performance  of any of the terms of this Warrant,  and
will at all times in good faith carry out all the provisions of this Warrant and
take all action as may be  required  to protect the rights of the holder of this
Warrant.  Without limiting the generality of the foregoing, the Company (i) will
not  increase the par value of any shares of Common  Stock  receivable  upon the
exercise of this Warrant above the Exercise Price then in effect, (ii) will take
all such actions as may be necessary  or  appropriate  in order that the Company
may  validly and legally  issue  fully paid and  nonassessable  shares of Common
Stock upon the exercise of this  Warrant,  and (iii) will, so long as any of the
SPA  Warrants  are  outstanding,  take all action  necessary to reserve and keep
available  out of its  authorized  and  unissued  Common  Stock,  solely for the
purpose of effecting the exercise of the SPA  Warrants,  the number of shares of
Common  Stock as shall from time to time be  necessary to effect the exercise of
the  SPA  Warrants  then  outstanding  (without  regard  to any  limitations  on
exercise) in accordance with Section 3(c) of the Securities Purchase Agreement.

     6.  WARRANT   HOLDER  NOT  DEEMED  A   STOCKHOLDER.   Except  as  otherwise
specifically  provided herein, no holder,  solely in such Person's capacity as a
holder,  of this  Warrant  shall be entitled to vote or receive  dividends or be
deemed the holder of shares of the Company for any purpose,  nor shall  anything
contained in this Warrant be construed to confer upon the holder hereof,  solely
in such Person's  capacity as a holder of this  Warrant,  any of the rights of a
shareholder of the Company or any right to vote, give or withhold consent to any
corporate action (whether any reorganization,  issue of stock,  reclassification
of stock,  consolidation,  merger,  conveyance or otherwise),  receive notice of
meetings,  receive dividends or subscription rights, or otherwise,  prior to the
issuance to the holder of this  Warrant of the Warrant  Shares which such Person
is then entitled to receive upon the due exercise of this Warrant.  In addition,
nothing contained in this Warrant shall be construed as imposing any liabilities
on such holder to purchase  any  securities  (upon  exercise of this  Warrant or
otherwise)  or as a stockholder  of the Company,  whether such  liabilities  are
asserted by the Company or by  creditors of the  Company.  Notwithstanding  this
Section 6, the Company  will  provide the holder

                                      -11-
<PAGE>

of this Warrant with copies of the same notices and other  information  given to
the  stockholders of the Company  generally,  contemporaneously  with the giving
thereof to the stockholders.

     7. REISSUANCE OF WARRANTS.


          (a)  Transfer  of Warrant.  If this  Warrant is to be  transferred  in
compliance with the provisions  hereof,  the holder shall surrender this Warrant
to the Company,  whereupon the Company will forthwith issue and deliver upon the
order of the holder of this  Warrant a new Warrant (in  accordance  with Section
7(d)),  registered as the holder of this Warrant may request,  representing  the
right to purchase the number of Warrant  Shares being  transferred by the Holder
and,  if less then the total  number of  Warrant  Shares  then  underlying  this
Warrant is being transferred, a new Warrant (in accordance with Section 7(d)) to
the holder of this  Warrant  representing  the right to  purchase  the number of
Warrant Shares not being transferred.

          (b) Lost, Stolen or Mutilated Warrant.  Upon receipt by the Company of
evidence reasonably satisfactory to the Company of the loss, theft,  destruction
or mutilation of this Warrant,  and, in the case of loss,  theft or destruction,
of any indemnification  undertaking by the holder of this Warrant to the Company
in  customary  form  and,  in  the  case  of  mutilation,   upon  surrender  and
cancellation  of this  Warrant,  the  Company  shall  execute and deliver to the
Holder a new Warrant (in accordance with Section 7(d)) representing the right to
purchase the Warrant Shares then underlying this Warrant.

          (c)  Warrant  Exchangeable  for  Multiple  Warrants.  This  Warrant is
exchangeable, upon the surrender hereof by the Holder at the principal office of
the Company,  for a new Warrant or Warrants (in  accordance  with Section  7(d))
representing in the aggregate the right to purchase the number of Warrant Shares
then underlying this Warrant, and each such new Warrant will represent the right
to purchase  such portion of such Warrant  Shares as is designated by the holder
of this  Warrant  at the  time of such  surrender;  provided,  however,  that no
Warrants for fractional shares of Common Stock shall be given.

          (d)  Issuance  of New  Warrants.  Whenever  the Company is required to
issue a new Warrant pursuant to the terms of this Warrant,  such new Warrant (i)
shall be of like tenor with this Warrant, (ii) shall represent,  as indicated on
the face of such new  Warrant,  the right to purchase  the  Warrant  Shares then
underlying  this Warrant (or in the case of a new Warrant being issued  pursuant
to Section 7(a) or Section 7(c), the Warrant Shares  designated by the holder of
this  Warrant  which,  when  added to the  number  of  shares  of  Common  Stock
underlying the other new Warrants issued in connection with such issuance,  does
not exceed the number of Warrant Shares then  underlying  this  Warrant),  (iii)
shall have an issuance  date, as indicated on the face of such new Warrant which
is the same as the  Issuance  Date,  and (iv)  shall  have the same  rights  and
conditions as this Warrant.

     8.  NOTICES.  Whenever  notice is required to be given under this  Warrant,
unless otherwise provided herein,  such notice shall be given in accordance with
Section 9(f) of the Securities Purchase Agreement. The Company shall provide the
holder of this Warrant with prompt  written notice of all actions taken pursuant
to this Warrant, including in reasonable detail a description of such action and
the reason  therefore.  Without  limiting the generality of the

                                      -12-
<PAGE>

foregoing,  the Company will give  written  notice to the holder of this Warrant
(i)  immediately  upon any  adjustment of the Exercise  Price,  setting forth in
reasonable detail,  and certifying,  the calculation of such adjustment and (ii)
at least seven days prior to the date on which the  Company  closes its books or
takes a record (A) with respect to any dividend or distribution  upon the Common
Stock,  (B)  with  respect  to any  grants,  issues  or  sales  of any  Options,
Convertible  Securities  or rights to purchase  stock,  warrants,  securities or
other property to holders of Common Stock or (C) for determining  rights to vote
with  respect  to any  Change of Control  (as  defined  in the SPA  Securities),
dissolution or liquidation, provided in each case that such information shall be
made known to the  public  prior to or in  conjunction  with such  notice  being
provided to such  holder.  Notwithstanding  the  foregoing,  Section 4(i) of the
Securities  Purchase Agreement shall apply to all notices given pursuant to this
Warrant.

     9.  AMENDMENT  AND  WAIVER.   Except  as  otherwise  provided  herein,  the
provisions  of this  Warrant  may be amended and the Company may take any action
herein prohibited, or omit to perform any act herein required to be performed by
it, only if the Company has obtained  the written  consent of the holders of SPA
Warrants  representing  at  least  two-thirds  of the  shares  of  Common  Stock
obtainable upon exercise of the SPA Warrants then outstanding;  provided that no
such action may increase  the exercise  price of any SPA Warrant or decrease the
number of shares or class of stock  obtainable  upon exercise of any SPA Warrant
without the written  consent of the holder of this  Warrant.  No such  amendment
shall be effective to the extent that it applies to less than all of the holders
of the SPA Warrants then outstanding.

     10.  GOVERNING  LAW.  This  Warrant  shall be  construed  and  enforced  in
accordance  with,  and all  questions  concerning  the  construction,  validity,
interpretation  and  performance  of this  Warrant  shall be  governed  by,  the
internal laws of the State of New York,  without  giving effect to any choice of
law or conflict of law  provision  or rule  (whether of the State of New York or
any other  jurisdictions)  that would cause the  application  of the laws of any
jurisdictions other than the State of New York.

     11.  CONSTRUCTION;  HEADINGS.  This  Warrant  shall be deemed to be jointly
drafted by the Company and all the Purchasers and shall not be construed against
any  person  as the  drafter  hereof.  The  headings  of  this  Warrant  are for
convenience   of   reference   and  shall  not  form  part  of,  or  affect  the
interpretation of, this Warrant.

     12. DISPUTE RESOLUTION. In the case of a dispute as to the determination of
the Exercise Price or the  arithmetic  calculation  of the Warrant  Shares,  the
Company shall submit the disputed  determinations or arithmetic calculations via
facsimile within two Business Days of receipt of the Exercise Notice giving rise
to such  dispute,  as the case may be,  to the  holder of this  Warrant.  If the
holder  of  this  Warrant  and  the  Company  are  unable  to  agree  upon  such
determination  or calculation of the Exercise Price or the Warrant Shares within
three  Business Days of such disputed  determination  or arithmetic  calculation
being submitted to the Holder,  then the Company shall, within two Business Days
submit via facsimile (a) the disputed  determination of the Exercise Price to an
independent,  reputable  investment bank selected by the Company and approved by
the holder of this Warrant or (b) the  disputed  arithmetic  calculation  of the
Warrant Shares to the Company's  independent,  outside  accountant.  The Company
shall  cause  the  investment  bank or the  accountant,  as the case may be,  to
perform the determinations

                                      -13-
<PAGE>

or  calculations  and notify the  Company and the Holder of the results no later
than ten Business Days from the time it receives the disputed  determinations or
calculations.   Such  investment   bank's  or  accountant's   determination   or
calculation,  as the  case may be,  shall be  binding  upon all  parties  absent
demonstrable error.

     13.  REMEDIES,  OTHER  OBLIGATIONS,  BREACHES AND  INJUNCTIVE  RELIEF.  The
remedies  provided in this Warrant  shall be  cumulative  and in addition to all
other remedies available under this Warrant,  the Securities Purchase Agreement,
the SPA Securities and the Registration  Rights  Agreement,  at law or in equity
(including a decree of specific performance and/or other injunctive relief), and
nothing  herein  shall  limit the right of the holder of this  Warrant  right to
pursue actual damages for any failure by the Company to comply with the terms of
this Warrant.  The Company  acknowledges  that a breach by it of its obligations
hereunder will cause irreparable harm to the holder of this Warrant and that the
remedy at law for any such  breach  may be  inadequate.  The  Company  therefore
agrees that, in the event of any such breach or threatened breach, the holder of
this Warrant shall be entitled,  in addition to all other available remedies, to
an injunction  restraining any breach, without the necessity of showing economic
loss and without any bond or other security being required.

     14. TRANSFER.  This Warrant may be offered for sale,  sold,  transferred or
assigned without the consent of the Company, except as may otherwise be required
by Section 2(f) of the Securities  Purchase  Agreement or any other provision of
this Warrant.

     15. CERTAIN DEFINITIONS.  For purposes of this Warrant, the following terms
shall have the following meanings:

          (a) "Bloomberg" means Bloomberg Financial Markets.

          (b) "Business Day" means any day other than Saturday,  Sunday or other
day on which commercial banks in The City of New York are authorized or required
by law to remain closed.

          (c)  "Closing  Bid Price" and  "Closing  Sale  Price"  means,  for any
security  as of any date,  the last  closing  bid price and last  closing  trade
price,  respectively,  for such security on the Principal Market, as reported by
Bloomberg,  or, if the Principal  Market begins to operate on an extended  hours
basis and does not  designate  the closing bid price or the closing trade price,
as the case may be, then the last bid price or last trade  price,  respectively,
of such security prior to 4:00:00 p.m., New York Time, as reported by Bloomberg,
or, if the Principal Market is not the principal  securities exchange or trading
market  for such  security,  the last  closing  bid price or last  trade  price,
respectively,  of such security on the principal  securities exchange or trading
market where such security is listed or traded as reported by  Bloomberg,  or if
the  foregoing  do not apply,  the last  closing bid price or last trade  price,
respectively,  of such security in the over-the-counter market on the electronic
bulletin board for such security as reported by Bloomberg, or, if no closing bid
price or last trade  price,  respectively,  is  reported  for such  security  by
Bloomberg,  the average of the bid prices, or the ask prices,  respectively,  of
any market  makers for such  security as  reported in the "pink  sheets" by Pink
Sheets LLC (formerly the National  Quotation  Bureau,  Inc.). If the Closing Bid
Price or the  Closing  Sale  Price  cannot be  calculated for a

                                      -14-
<PAGE>

security on a particular  date on any of the  foregoing  bases,  the Closing Bid
Price or the Closing  Sale Price,  as the case may be, of such  security on such
date shall be the fair market  value as mutually  determined  by the Company and
the  Holder.  If the  Company  and the  Holder are unable to agree upon the fair
market value of such security,  then such dispute shall be resolved  pursuant to
Section 12. All such  determinations to be appropriately  adjusted for any stock
dividend, stock split, stock combination or other similar transaction during the
applicable calculation period.

          (d) "Common  Stock" means (i) the Company's  common  stock,  par value
$0.001 per share,  and (ii) any capital stock into which such Common Stock shall
have been changed or any capital stock resulting from a reclassification of such
Common Stock.

          (e) "Common Stock Deemed  Outstanding"  means,  at any given time, the
number of shares of Common Stock  actually  outstanding  at such time,  plus the
number of shares of Common Stock deemed to be  outstanding  pursuant to Sections
2(a)(i) and 2(a)(ii)  hereof  regardless  of whether the Options or  Convertible
Securities  are actually  exercisable or convertible at such time, but excluding
any shares of Common Stock owned or held by or for the account of the Company or
issuable upon conversion of the SPA Securities or exercise of the SPA Warrants.

          (f) "Convertible Securities" means any stock or securities (other than
Options) directly or indirectly  convertible into or exercisable or exchangeable
for Common Stock.

          (g) "Excluded  Securities"  means any shares of Common Stock issued or
issuable (i) in  connection  with one or more  strategic  partnerships  or joint
ventures  in  which  there is a  significant  commercial  relationship  with the
Company and in which the primary purpose of which is not to raise capital, in an
amount  not to  exceed,  in the  aggregate,  gross  proceeds  to the  Company of
$20,000,000 or an aggregate of 10,000,000  shares,  (ii) pursuant to a bona fide
firm  commitment  underwritten  public  offering  with a  nationally  recognized
underwriter  which  generates  gross  proceeds  to  the  Company  in  excess  of
$45,000,000 (other than an "at-the-market offering" as defined in Rule 415(a)(4)
under the 1933 Act and "equity  lines") and (iii) upon conversion of any Options
or Convertible Securities which are outstanding on the day immediately preceding
the  Initial  Issuance  Date,  provided  that  the  terms  of  such  Options  or
Convertible  Securities  are not  amended,  modified  or changed on or after the
Initial Issuance Date.

          (h) "Expiration Date" means the date five years after the Closing Date
(as defined in the Securities Purchase Agreement) pursuant to which this Warrant
was  initially  issued or, if such date falls on a day other than a Business Day
or on which trading does not take place on the Principal  Market (a  "Holiday"),
the next date that is not a Holiday.

          (i) "Options"  means any rights,  warrants or options to subscribe for
or purchase Common Stock or Convertible Securities.

                                      -15-
<PAGE>

          (j) "Person"  means an  individual,  a limited  liability  company,  a
partnership,  a  joint  venture,  a  corporation,  a  trust,  an  unincorporated
organization,  any other entity and a  government  or any  department  or agency
thereof.

          (k)  "Principal  Market"  means The NASDAQ  National  Market or in the
event that the Company is no longer listed with The NASDAQ National Market,  the
market or  exchange on which the Common  Stock is then listed and traded,  which
only may be The New York Stock  Exchange,  Inc.,  the American Stock Exchange or
The NASDAQ SmallCap Market.

          (l) "Registration  Rights  Agreement" means that certain  registration
rights agreement between the Company and the Purchasers.

          (m) "SPA  Securities"  means the convertible  notes issued pursuant to
the Securities Purchase Agreement.


                            [Signature Page Follows]

                                      -16-
<PAGE>

     IN WITNESS WHEREOF,  the Company has caused this Warrant to Purchase Common
Stock to be duly executed as of the Issuance Date set out above.

                                    APHTON CORPORATION



                                    By:
                                       ------------------------------------
                                       Name:
                                       Title:

<PAGE>


                                                                       EXHIBIT A

                                 EXERCISE NOTICE

            TO BE EXECUTED BY THE REGISTERED HOLDER TO EXERCISE THIS
                        WARRANT TO PURCHASE COMMON STOCK

                               APHTON CORPORATION

     The undersigned holder hereby exercises the right to purchase ______ of the
shares of Common  Stock  ("Warrant  Shares") of Aphton  Corporation,  a Delaware
corporation  (the  "Company"),  evidenced  by the  attached  Warrant to Purchase
Common Stock (the  "Warrant").  Capitalized  terms used herein and not otherwise
defined shall have the respective meanings set forth in the Warrant.

     1. Form of Exercise Price.  The Holder intends that payment of the Exercise
Price shall be made as:

        ______ a "Cash Exercise" with respect to ______ Warrant Shares; and/or


        ______ a "Cashless Exercise" with respect to ______ Warrant Shares.

     2.  Payment of Exercise  Price.  In the event that the holder has elected a
Cash  Exercise  with  respect to some or all of the Warrant  Shares to be issued
pursuant hereto, the holder shall pay the Aggregate Exercise Price in the sum of
$_______ to the Company in accordance with the terms of the Warrant.

     3.  Delivery of Warrant  Shares.  The Company  shall  deliver to the holder
______ Warrant Shares in accordance with the terms of the Warrant.

Date:
     --------------- --, ----


-----------------------------
  Name of Registered Holder


By:
   --------------------------
   Name:
   Title:

<PAGE>


                                 ACKNOWLEDGMENT


     The Company  hereby  acknowledges  this Exercise  Notice and hereby directs
U.S. Stock Transfer Corporation to issue the above indicated number of shares of
Common Stock in accordance with the Transfer Agent  Instructions dated March 31,
2003 from the  Company and  acknowledged  and agreed to by U.S.  Stock  Transfer
Corporation.

                                              APHTON CORPORATION



                                              By:
                                                 -------------------------------
                                                 Name:
                                                 Title: