THE
SUBSCRIPTION RIGHTS WILL EXPIRE IF NOT EXERCISED ON OR BEFORE 5:00 PM., NEW YORK
CITY TIME, ON ________, 2011. THE TERMS AND CONDITIONS OF THE RIGHTS OFFERING
ARE SET FORTH IN THE COMPANY’S PROSPECTUS DATED
                  ,
2011 (THE “PROSPECTUS”) AND ARE INCORPORATED HEREIN BY REFERENCE, COPIES OF THE
PROSPECTUS ARE AVAILABLE UPON REQUEST FROM ADHEREX TECHNOLOGIES, INC OR THE
SUBSCRIPTION AGENT.

    


    
      
        
          	
                  EVIDENCING
      SUBSCRIPTION RIGHTS TO PURCHASE UNITS CONSISTING OF ONE (1) COMMON SHARE
      AND ONE (1) WARRANT TO PURCHASE COMMON SHARES OF ADHEREX TECHNOLOGIES
      INC.

                	 
      	
                  ADHEREX
      TECHNOLOGIES INC.

                	 
      	
                  CUSIP         00686R168

                  ISIN         CA00686R1689

                
	 
      	 
      	 
      	 
      	 
      
	
                  

                	 
      	
                  THIS
      C|ERTIFIES
      THAT:

                	 
      	
                  

                
	 
      	 
      	 
      	 
      	 
      
	
                  FORM 1-EXERCISE
      OF BASIC SUBSCRIPTION RIGHT

                   

                  I
      hereby irrevocably subscribe for the number of Units indicated below upon
      the terms and subject to the conditions stated in the Company's Prospectus
      at a subscription price of CAD $0.03 and acknowledge receipt of the
      Prospectus.

                   

                  NUMBER
      OF UNITS SUBSCRIBED FOR_________ AT CAD $0.03 PER UNIT.

                   

                  TOTAL
      PRICE: CAD$_________________

                   

                  SUBSCRIBER'S
      SIGNATURE:_________________

                  SIGNATURE
      MUST CORRESPOND IN EVERY PARTICULAR WITH YOUR NAME AS IT APPEARS ON THE
      FACE OF THIS CERTIFICATE

                   

                  Payment
      in full of the subscription price in U.S. or Canadian funds by certified
      check, bank draft or wire transfer (see “Instructions and
      Information for Certificate Holders” on back of this Certificate) must be
      made to Olympia Transfer Services, Inc. (for the benefit of Adherex
      Technologies, Inc.). with this subscription.

                   

                  IF
      THE SUBSCRIBER IS OTHER THAN THE ABOVE NAMED REGISTERED HOLDER OF THIS
      RIGHTS CERTIFICATE, FORM 3 MUST BE DULY COMPLETED STATING THE NAME AND THE
      ADDRESS OF THE TRANSFEREE.

                	 
        	
                   
      

                   

                   

                   

                   

                	 
        	
                  FORM
      3 - TRANSFER OF RIGHTS

                   

                  IF
      THE RIGHTS ARE SOLD THROUGH AN INVESTMENT DEALER OR STOCK BROKER, DO NOT
      FILL IN THE NAME AND ADDRESS OF THE
      TRANSFEREE.

                   

                  FOR
      VALUE RECEIVED [print name] _____________ (the “Subscription Rights
      Holder”) hereby sells, assigns and transfers unto [print name]
      ___________________ (the “Transferee”), at [print address]
      __________________,______________
      Subscription Rights to Purchase Units represented by this Certificate, and
      hereby irrevocably appoints Olympia
      Transfer Services, Inc. as the attorney of the undersigned to transfer the
      said securities on the books maintained by the Corporation, with full
      power of substitution.

                   

                  TO
      SUBSCRIBE FOR UNITS, THE TRANSFEREE MUST FILL IN THE ABOVE PARTICULARS AND
      ALSO COMPLETE FORM 1.

                   

                  Signature
      of rights certificateholder:__________________

                  SIGNATURE
      MUST CORRESPOND IN EVERY PARTICULAR WITH YOUR NAME AS IT APPEARS ON THE
      FACE OF THIS CERTIFICATE

                   

                  Signature
      Guaranteed by:_________________

                   

                  IMPORTANT: 
      The signature(s) must be guaranteed by (i) a major Canadian Schedule
      1 chartered bank, a member of the Securities Transfer Agents Medallion
      Program (STAMP), a member of the Stock Exchange Medallion Program (SEMP),
      or a member of the New York Stock Exchange Inc. Medallion Signature
      Program (MSP)  for Canadian holders, or (ii) by an eligible
      guarantor institution (bank, stock broker, savings & loan
      association or credit union) with membership in an approved signature
      guarantee medallion program pursuant to Securities Exchange Act of 1934
      Rule 17Ad-15 for U.S. holders.

                
	 
      	
                  is the owner of the
      number of transferable subscription rights (“Subscription Rights” or
      “Rights”) set forth on this Certificate.  Each whole Subscription
      Right entitles the holder thereof to subscribe for and purchase one Unit
      (each, a “Unit”), consisting of one (1) share of common stock, no par
      value (“Share”), and one (1) warrant to purchase one Share (“Warrant”), of
      Adherex Technologies, Inc. (the “Corporation”) at a subscription price of
      CAD$0.03, pursuant to a Subscription Rights Offering (the “Subscription
      Rights Offering”), on the terms and subject to the conditions set forth in
      the Prospectus and the “Instructions and Information for Certificate
      Holders” accompanying this Subscription Rights Certificate (“Subscription
      Rights Certificate” or “Certificate”).  The Subscription Rights
      represented by this Subscription Rights Certificate may be exercised by
      completing Form 1
      and any other appropriate forms on this Certificate and by returning the
      full payment of the subscription price for each Unit in accordance with
      the “Instructions and Information for Certificate Holders” that
      accompanies this Subscription Rights Certificate.  In
      connection with the exercise of Subscription Rights, subscriber is
      required to complete and sign the two (2) attached anti-money laundering
      forms in compliance with applicable Canadian anti-money laundering
      legislation and return the same to our Subscription Agent, Olympia
      Transfer Services,
      Inc.

                	 
      
	 
      	 
      	 
      	 
      	 
      
	
                  FORM
      2 – EXERCISE OF THE OVER-SUBSCRIPTION RIGHT

                   

                   I
      hereby irrevocably subscribe for up to that number of additional Units
      specified below pursuant to the Over-Subscription Right at a subscription
      price of CAD $0.03 per Unit and irrevocably agree to accept the same or
      any smaller number that may be allotted among those exercising this
      Over-Subscription Right in accordance with the procedure set out in the
      Prospectus.

                   

                  MAXIMUM
      NUMBER OF OVER-SUBSCRIPTION UNITS SUBSCRIBED FOR

                   

                  ______________AT
      CAD $0.03 PER UNIT

                   

                  TOTAL
      PRICE: CAD $_________________

                   

                  SUBSCRIBER'S
      SIGNATURE:__________________

                  SIGNATURE
      MUST CORRESPOND IN EVERY PARTICULAR WITH YOUR NAME AS IT APPEARS ON THE
      FACE OF THIS CERTIFICATE

                   

                  Payment
      in full of the subscription price for such additional Units in U.S. or
      Canadian funds by certified check, bank draft or wire transfer (see
      “Instructions and Information for Certificate Holders; Payment of
      Subscription Price”) must be made to Olympia Transfer Services, Inc. (for
      the benefit of Adherex Technologies, Inc.) with this subscription. In the
      event of there are an insufficient number of Units available to satisfy
      all exercised Over-Subscription Rights, our subscription agent shall
      return to subscribers the excess funds paid for subscription of such
      unavailable Units and the remaining Units available under the
      Over-Subscription Right will be allocated on a pro
      rata basis.

                	 
      	
                  ADHEREX
      TECHNOLOGIES INC.

                   

                   

                   

                   

                   

                  Secretary                 
                     Chief
      Executive Officer

                   

                  OLYMPIA
      TRANSFER SERVICES INC.

                   

                   

                   

                   

                  Authorized
      Signatory

                   

                  Date:
      _______________________

                   

                  SEE
      DIRECTIONS ON REVERSE AND COMPLETE

                  APPROPRIATE
      FORMS HEREOF

                	 
      	
                  FORM
      4 - TO DIVIDE OR COMBINE RIGHTS CERTIFICATES

                  Please
      deliver to the undersigned new rights certificate(s) in the name of the
      undersigned as indicated below. If a rights certificate is being divided,
      each new rights certificate must represent a whole number of
      rights.

                   

                  _____rights
      certificate(s) for_____ Rights each

                   

                  _____rights
      certificate(s) for_____ Rights each

                  Signature
      of rights certificate holder:_________________.

                  SIGNATURE
      MUST CORRESPOND IN EVERY PARTICULAR WITH YOUR NAME AS IT APPEARS ON THE
      FACE OF THIS CERTIFICATE

                   

                  FORM
      5 - DELIVERY TO DIFFERENT ADDRESS

                   

                  If
      you wish for the Shares and Warrants underlying your Rights, to be
      delivered to an address different from that which is on the records of the
      Corporation (i.e., the address at which this Certificate was initially
      received), please enter the alternate address below, sign below and have
      your signature guaranteed.

                  ______________________________

                  [Print
      address]

                   

                  Signature
      of rights certificate holder:________________

                  SIGNATURE
      MUST CORRESPOND IN EVERY PARTICULAR WITH YOUR NAME AS IT APPEARS ON THE
      FACE OF THIS CERTIFICATE

                   

                  Signature
      Guaranteed by:__________________

                   

                  IMPORTANT: 
      The signature(s) must be guaranteed (i) by a major Canadian Schedule
      1 chartered bank, a member of the Securities Transfer Agents Medallion
      Program (STAMP), a member of the Stock Exchange Medallion Program (SEMP),
      or a member of the New York Stock Exchange Inc. Medallion Signature
      Program (MSP)  for Canadian holders, or (ii) by an eligible
      guarantor institution (bank, stock broker, savings & loan
      association or credit union) with membership in an approved signature
      guarantee medallion program pursuant to Securities Exchange Act of 1934
      Rule 17Ad-15 for U.S.
holders.

                


        

      

    


    
      
         


      

      
        
        

        
          

        

      

      
         


      

    


    INSTRUCTIONS
AND INFORMATION FOR CERTIFICATE HOLDERS

    


    
      	
              1.

            	
              TO SUBSCRIBE FOR
      SHARES

            


    

    Fill in
and sign Form 1 and Form 2 (if exercising the Over-Subscription Right) on the
face hereof on the line "Signature(s)" making certain that your signature
corresponds in every particular with your name as it appears on the face of this
Certificate. Subscriptions will only be accepted for a whole number of
Units.  A bank, trust company, securities dealer or broker which holds
Units for more than one beneficial owner may, upon providing evidence
satisfactory to Olympia Transfer Services Inc., exercise the Rights evidenced by
this Certificate or exchange its Certificate on the same basis as if the
beneficial owners were registered holders. Rights certificates for fractional
interests shall not be issued and any fractional rights will be eliminated by
rounding down to the nearest whole right. If Form 1 is completed so as to
exercise some but not all of the Rights represented by this Certificate, the
Subscription Rights Holder will be deemed to have waived the unexercised balance
of such Rights at the time this Certificate is surrendered, unless the
Subscription Rights Holder has provided that the Rights are to be transferred to
a third party or are to be retained by the Subscription Rights Holder in the
appropriate Forms on this Certificate or otherwise by advising
the subscription agent in writing.  Mail or deliver this Certificate
with full payment for the subscription price for all Units subscribed for
to:

    


    Olympia
Transfer Services Inc.

    Suite
920, 120 Adelaide St W

    Toronto,
Ontario M5H 1T1

    Attention:
Corporate Actions

    


    To be a
valid subscription, the appropriate Forms on this Certificate, along with the
two (2) anti-money laundering forms attached hereto, must be duly completed, and
the required payment must be received by Olympia Transfer Services Inc. at the
above offices on or before 5:00 p.m. (New York City Time) on _________, 2011
("Expiry
Date").  For your own protection, if forwarding by mail, it is
suggested that overnight courier or registered mail (return receipt requested)
be used.  Subject to the satisfaction of conditions herein and in the
Prospectus, certificates for the Shares and Warrants as subscribed for will be
mailed to you by first class mail at your last recorded address on the records
of Adherex Technologies, Inc. (the “Corporation”), or if a different address,
the address provided in Form 5 (assuming such form is duly completed and signed
with your signature guaranteed), or in the case of a transferee exercising
transferred Rights, at the address indicated in Form 3, as soon as
practicable.  This Certificate does not entitle the holder to any
rights whatsoever as a shareholder of the Corporation.

    


    
      	
              2.

            	
              TO SELL OR TRANSFER
      RIGHTS

            


    

    Complete
Form 3 on the face hereof, sign, and have your signature guaranteed (i) by a
major Canadian Schedule 1 chartered bank, a member of the Securities Transfer
Agents Medallion Program (STAMP), a member of the Stock Exchange Medallion
Program (SEMP), or a member of the New York Stock Exchange Inc. Medallion
Signature Program (MSP) for Canadian holders, or (ii) by an eligible guarantor
institution (bank, stock broker, savings & loan association or credit
union) with membership in an approved signature guarantee medallion program
pursuant to Securities Exchange Act of 1934 Rule 17Ad-15 for U.S. holders,
and deliver this Certificate to Olympia Transfer Services, Inc.  Your
signature must correspond in every particular with your name as it appears on
the face of this Certificate. IF FORM 1 IS PROPERLY COMPLETED, THE SUBSCRIPTION
PRICE PAID, AND ALL OTHER REQUIREMENTS TO BE A VALID SUBSCRIPTION ARE SATISFIED,
THE TRANSFEREE MAY USE THIS CERTIFICATE FOR SUBSCRIPTION WITHOUT OBTAINING A NEW
CERTIFICATE. A sale or transfer should be accompanied by delivery of this
Certificate in ample time so that it can be used before the Expiry
Date.

    


    
      	
              3.

            	
              PAYMENT OF SUBSCRIPTION
      PRICE

            


    

    The total
subscription price for the number of Units specified in Form 1 and, if
applicable, Form 2, must be paid in full in either Canadian dollars or U.S.
dollars, by certified check or bank draft payable to Olympia Transfer Services,
Inc. (for the benefit of Adherex Technologies
Inc.).  If  the subscriber elects to pay the subscription
price in U.S. Dollars, the subscription price shall be calculated based on an
exchange rate of [_____] (the US/Canadian currency exchange rate in effect on
February XX, 2011).  Funds paid by uncertified check may take at least
five (5) business days to clear. Your subscription may not be considered
accepted until such check has cleared. Payment can be made by way of wire
transfer, contact the subscription agent at (416) 364-8081 or
infotoronto@olympiatrust.com.

    


    
      	
              4.

            	
              VALIDITY AND REJECTION OF
      SUBSCRIPTIONS

            


    

    All
questions as to the validity, form, eligibility (including time of receipt) and
acceptance of any subscription will be determined by the Corporation in its sole
discretion, whose determination shall be final and binding.  All
subscriptions are irrevocable.  The Corporation reserves the right to
reject any subscription if such subscription is not in proper form or if the
acceptance thereof or the issuance of Shares and Warrants pursuant thereto could
be deemed unlawful.  The Corporation also reserves the right to waive
any defect with regard to any particular subscription.  Neither the
Corporation nor Olympia Transfer Services Inc. will be under any duty to give
any notification of any defect of irregularity in such subscriptions nor shall
either of them incur any liability for failure to give such
notification.

    


    
      	
              5.

            	
              DIVIDE OR COMBINE
      CERTIFICATES

            


    

    Certificates
may be combined or divided upon surrender of the original certificate(s) by
completing and executing Form 4 and delivering this Certificate to Olympia
Transfer Services Inc. at the above offices in ample time for the new
certificate(s) to be issued before the Expiry Date.  New
certificate(s) will be issued in the same name as that reflected on the
Certificate(s) surrendered.

    


    
      	
              6.

            	
              DELIVERY TO A DIFFERENT
      ADDRESS

            


    

    If you
wish for the Shares and Warrants underlying your Rights, to be delivered to an
address different from that which is reflected in the records of the Corporation
(i.e., the address at which the Rights Certificate was initially received),
please enter the alternate address on Form 5, sign and have your signature
guaranteed under Form 5.

    


    
      	
              7.

            	
              EVIDENCE OF
      AUTHORITY

            


    

    If a form
is signed by a trustee, executor, administrator, tutor, curator, guardian,
attorney, officer of a corporation or representative capacity, this Certificate
should be accompanied by evidence of authority satisfactory to Olympia Transfer
Services Inc.

    


    THESE
RIGHTS AND THIS CERTIFICATE WILL BE VOID AND HAVE NO VALUE AFTER 5:00 P.M. (NEW
YORK CITY TIME) ON ____________, 2011 AND ANY TRANSFER, COMBINATION, DIVISION OR
EXCHANGE OF THIS CERTIFICATE MUST BE COMPLETED IN TIME TO PERMIT EXERCISE ON OR
BEFORE SUCH DATE AND TIME.