<PAGE>
                                                                     EXHIBIT 4.3

                                     WARRANT
                                       TO
                 PURCHASE ______ SHARES OF CLASS A COMMON STOCK
                                       OF
                               BIOPURE CORPORATION
                            (A DELAWARE CORPORATION)

Warrant No. ___

     THIS CERTIFIES THAT, for value received, _______ or its assigns, (the
"HOLDER"), as registered owner of this warrant (the "WARRANT"), is entitled to
purchase and receive, in whole or in part, subject to the provisions of this
Warrant, from Biopure Corporation, a Delaware corporation (the "COMPANY"), up to
____ fully paid, validly issued and nonassessable shares of Class A common
stock, par value $.01 per share (the "COMMON STOCK"), of the Company (the
"WARRANT SHARES") at a price per share equal to $0.984 (the "INITIAL EXERCISE
PRICE") (120% of the initial public offering price per share); provided,
however, that the number and kind of securities for which the Warrants are
exercisable are subject to further adjustment in certain events, such as
mergers, splits, stock dividends, recapitalizations and the like, to prevent
dilution, as set forth herein. This Warrant shall be exercisable at any time and
from time to time during the period commencing one (1) year after (the
"COMMENCEMENT DATE") the date of hereof up to and including January 17, 2011
(the "EXPIRATION DATE"), and subject to the terms and conditions set forth
herein. If the Expiration Date is a day on which banking institutions are
authorized by law to close, then this Warrant may be exercised on the next
succeeding day which is not such a day in accordance with the terms herein.
During the period beginning on the Commencement Date and ending on the
Expiration Date, the Company agrees not to take any action that would terminate
the Warrant.

     Section 1. Exercise.

               Section 1.1 Exercise Form. In order to exercise this Warrant, the
     exercise form attached hereto must be duly executed and completed and
     delivered to the Company, together with this Warrant and payment of the
     Exercise Price in cash or by certified check or official bank check for the
     Warrant Shares being purchased. If the subscription rights represented
     hereby shall not be exercised at or before 5:00 p.m., Eastern time, on the
     Expiration Date, this Warrant shall become and be void without further
     force or effect, and all rights represented hereby shall cease and expire.

               Section 1.2 Conversion Right.

                    Section 1.2.1 Determination of Amount. In lieu of the
     payment of the Exercise Price in the manner required by Section 1.1, the
     Holder shall have the right (but not the obligation) to convert any
     exercisable but unexercised portion of this Warrant into Warrant Shares
     (the "CONVERSION RIGHT") as follows. Upon exercise of the Conversion Right,
     the Company shall deliver to the Holder (without payment by the Holder of
     any of the Exercise Price in cash) that number of Warrant Shares equal to
     the quotient obtained by dividing (x) the "VALUE" (as defined below), at
     the close of trading on the next to last trading day immediately preceding
     the exercise of the Conversion Right, of the portion of the Warrant being
     converted by (y) the "MARKET PRICE" (as defined below). The "VALUE" of the
     portion of the Warrant being converted shall equal the remainder derived
     from subtracting (a) the Exercise Price multiplied by the number of Warrant

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     Shares underlying that portion of the Warrant being converted from (b) the
     Market Price of the Warrant Shares multiplied by the number of Warrant
     Shares underlying that portion of the Warrant being converted. As used in
     this herein, the term "MARKET PRICE" at any date shall be deemed to be the
     sum of (A) the average last reported sale price of the shares for the five
     trading days ending on the next to last trading day immediately preceding
     the exercise of the Conversion Right as officially reported by the
     principal securities exchange on which the shares are listed or admitted to
     trading, or, if the shares are not listed or admitted to trading on any
     national securities exchange or if any such exchange on which the shares
     are listed is not its principal trading market, the average last reported
     sale price for such five trading days as furnished by the NASD through the
     Nasdaq National Market or Capital Market, or, if applicable, the OTC
     Bulletin Board, or if the shares are not listed or admitted to trading on
     any of the foregoing markets, or similar organization, as determined in
     good faith by resolution of the Board of Directors of the Company, based on
     the best information available to it and (B) the intrinsic value of the
     Warrant using the share price determined in (A).

                    Section 1.2.2 Mechanics of Conversion. The Conversion Right
     may be exercised by the Holder on any business day on or after the
     Commencement Date and not later than the Expiration Date by delivering the
     Warrant with a duly executed exercise form attached hereto with the
     Conversion Right section completed to the Company, exercising the
     Conversion Right and specifying the total number of Warrant Shares that the
     Holder will purchase pursuant to such Conversion Right.

               Section 1.3 Notwithstanding anything to the contrary herein,
     after the sixth (6th) month anniversary of the date hereof, the Company
     may, by written notice to the Holder, require that the Holder execute and
     deliver to the Company an Exercise Notice exercising all of the Warrant
     Shares then held by such Holder within twenty (20) Business Days of the
     date of the Company's notice; provided, however, that the Company may only
     provide such notice if the daily volume weighted average price per share of
     the Common Stock for each of the ten (10) consecutive trading days ended
     immediately prior to the Company's notice is equal to or greater than the
     Exercise Price multiplied by 1.5. At 5:00 P.M. New York City time on such
     twentieth (20th) Business Day, the portion of this Warrant not exercised
     prior thereto shall be and become void and of no value, and the Holder
     hereof shall have no right to purchase any additional Warrant Shares
     hereunder.


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     Section 2. Transfer.

               Section 2.1 General Restrictions. The registered Holder of this
     Warrant, by its acceptance hereof, agrees that it will not sell, transfer
     or assign or hypothecate this Warrant prior to the one hundred eighty (180)
     days from the Effective Date to anyone other than (i) an officer or partner
     of such Holder, (ii) an officer of either Dawson James Securities, Inc. or
     Noble International Investments, Inc., the underwriters of the public
     offering with respect to which this Warrant has been issued
     ("UNDERWRITERS") or an officer or partner of any selected dealer in
     connection with the Company's public offering with respect to which this
     Warrant has been issued, or (iii) any selected dealer. On and after the
     Commencement Date, transfers to others may be made subject to compliance
     with or exemptions from applicable securities laws. In order to make any
     permitted assignment, the Holder must deliver to the Company the assignment
     form attached hereto duly executed and completed, together with the Warrant
     and payment of all transfer taxes, if any, payable in connection therewith.
     The Company shall immediately transfer this Warrant on the books of the
     Company and shall execute and deliver a new Warrant of like tenor to the
     appropriate assignee(s) expressly evidencing the right to purchase the
     aggregate number of Warrant Shares purchasable hereunder or such portion of
     such number as shall be contemplated by any such assignment.

               Section 2.2 Restrictions Imposed by the Act. This Warrant and the
     Warrant Shares underlying this Warrants shall not be transferred unless and
     until (i) the Company has received the opinion of counsel for the Holder
     that this Warrant or the Warrant Shares, as the case may be, may be
     transferred pursuant to an exemption from registration under the Act and
     applicable state law, the availability of which is established to the
     reasonable satisfaction of the Company (the Company hereby agreeing that an
     opinion of Cozen O'Connor shall be deemed satisfactory evidence of the
     availability of an exemption), or (ii) a registration statement relating to
     such Warrant or Warrant Shares, as the case may be, has been filed by the
     Company and declared effective by the Securities and Exchange Commission
     (the "COMMISSION") and compliance with applicable state law.

     Section 3. New Warrants to be Issued.

               Section 3.1 Partial Exercise or Transfer. Subject to the
     restrictions in Section 3 hereof, this Warrant may be exercised or assigned
     in whole or in part. In the event of the exercise or assignment hereof in
     part only, upon surrender of this Warrant for cancellation, together with
     the duly executed exercise or assignment form and funds sufficient to pay
     any Exercise Price and/or transfer tax, the Company shall cause to be
     delivered to the Holder without charge a new Warrant of like tenor to this
     Warrant in the name of the Holder evidencing the right of the Holder to
     purchase the aggregate number of Warrant Shares purchasable hereunder as to
     which this Warrant has not been exercised or assigned.

               Section 3.2 Lost Certificate. Upon receipt by the Company of
     evidence satisfactory to it of the loss, theft, destruction or mutilation
     of this Warrant and of reasonably satisfactory indemnification, and upon
     surrender and cancellation of the Warrants, if mutilated, the Company shall
     execute and deliver a new Warrant of like tenor and date. Any such new
     Warrant executed and delivered as a result of such loss, theft, mutilation
     or destruction shall constitute a substitute contractual obligation on the
     part of the Company.


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<PAGE>

     Section 4. Registration Rights.

               Section 4.1 Registration. This Warrant and the Warrant Shares
     issuable upon exercise of the Warrant (the Warrant and Warrant Shares
     collectively referred to hereinafter as the "REGISTRABLE SECURITIES") shall
     be registered pursuant to the Registration Statement (as defined
     hereinbelow), and the Company covenants and agrees to maintain the
     effectiveness of the Registration Statement until the Expiration Date.
     Notwithstanding the foregoing, in the event that, prior to the Expiration
     Date, the Company ceases to be eligible under the Securities Act of 1933,
     as amended (the "ACT") or the rules and regulations promulgated thereunder,
     to maintain a registration statement on Form S-3, or in the event that the
     Warrant or the Warrant Shares cease to be eligible for inclusion in such
     Registration Statement to the extent necessary to permit the Holder to
     exercise the Warrants and sell the Warrant Shares without restriction under
     the Act, the Company will promptly (and in any event within 10 days of the
     date that the Warrants or any Warrant Shares cease to be so eligible),
     amend or file a new registration statement under the Act on a form eligible
     for use by the Company for the registration of such securities and use its
     best efforts to have such registration statement declared effective by the
     Commission as soon as practicable after such filing, which registration
     statement shall include such information as may be required to permit the
     exercise of the Warrant and the sale of the Warrant Shares without
     restriction under the Act. The Holder acknowledges and agrees that the
     Warrant shall be exercisable pursuant to any such registration statement
     only at such times as the registration statement is effective or in
     accordance with any applicable exemption from the registration requirements
     of the Act. Upon such Registration Statement's being declared effective by
     the Commission, the Company shall use its best efforts to cause the
     Registration Statement to remain effective for a period of at least six (6)
     consecutive months from the date that the holders of the Warrant and the
     Warrant Shares are covered by such Registration Statement are first given
     the opportunity to sell all of such securities. During such time as the
     Warrant Shares registered pursuant to any registration statement under the
     Act, the Company further covenants and agrees to make timely filings of all
     documents required by be filed under the Act or the Exchange Act in order
     to ensure that the registration statement, including the documents
     incorporated by reference therein, if any, do not contain an untrue
     statement of a material fact or omit to state any material fact required to
     be stated therein or necessary in order to make the statements therein not
     misleading.

          "REGISTRATION STATEMENT" means the Company's Registration Statement
(File Nos. 333-114559), as such registration statements are amended,
supplemented, or replaced.


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               Section 4.2 Expenses. The Company shall bear all fees and
     expenses attendant to registering the Registrable Securities.

               Section 4.3 Exercise of Warrants. Nothing contained in this
     Warrant shall be construed as requiring the Holder(s) to exercise their
     Warrants prior to or after the initial filing of any registration statement
     or the effectiveness thereof.

               Section 4.4 Documents to be Delivered by Holder(s). Each of the
     Holder(s) participating in any of the foregoing offerings shall furnish to
     the Company a completed and executed questionnaire provided by the Company
     requesting information customarily sought of selling securityholders.

               Section 4.5 Remedies. The Company stipulates that the remedies at
     law of the Holder of this Warrant in the event of any default or threatened
     default by the Company in the performance of or compliance with any of the
     terms of this Warrant are not and will not be adequate, and that such terms
     may be specifically enforced by a decree for the specific performance of
     any agreement contained herein or by an injunction restraining any breach,
     actual or threatened, of the terms of this Warrant, without the necessity
     of showing economic loss. The remedies provided herein shall be cumulative
     and in addition to all other remedies available under this Warrant, at law
     or in equity, and nothing herein shall limit the right of the Holder to
     pursue actual damages for any failure by the Company to comply with the
     terms of the Warrant.

     Section 5. Adjustments.

               Section 5.1 Adjustments to Exercise Price and Number of
     Securities. The Exercise Price and the number of the Warrant Shares
     underlying the Warrant shall be subject to adjustment from time to time as
     hereinafter set forth:

                    Section 5.1.1 If after the date hereof, and subject to the
     provisions of Section 5.2 below, the number of outstanding shares of Common
     Stock is increased by a stock dividend payable in shares of Common Stock or
     by a split-up of shares of Common Stock or other similar event, then, on
     the effective date thereof, the number of shares of Common Stock underlying
     the Warrant shall be increased in proportion to such increase in
     outstanding shares.

                    Section 5.1.2 If after the date hereof, and subject to the
     provisions of Section 5.2, the number of outstanding shares of Common Stock
     is decreased by a consolidation, combination or reclassification of shares
     of Common Stock or other similar event, then, on the effective date
     thereof, the number of shares of Common Stock underlying the Warrant shall
     be decreased in proportion to such decrease in outstanding shares.

                    Section 5.1.3 In case of any reclassification or
     reorganization of the outstanding shares of Common Stock other than a
     change covered by Section 5.1.1 or 5.1.2 hereof or that solely affects the
     par value of such shares of Common Stock, or in the case of any merger or
     consolidation of the Company with or into another corporation (other than a
     consolidation or merger in which the Company is the continuing corporation
     and that does not result in any reclassification or reorganization of the
     outstanding shares of Common Stock), or in the case of any sale or
     conveyance to another corporation or entity of the property of the Company
     as an entirety or substantially as an entirety in connection with which the
     Company is dissolved, the Holder of this Warrant shall have the right
     thereafter (until the expiration of the right of exercise of this Warrant)
     to receive upon the exercise hereof, for the same aggregate Exercise Price
     payable hereunder immediately prior to such event, the kind and amount of
     shares of stock or other


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     securities or property (including cash) receivable upon such
     reclassification, reorganization, merger or consolidation, or upon a
     dissolution following any such sale or transfer, by a Holder of the number
     of shares of Common Stock of the Company obtainable upon exercise of this
     Warrant immediately prior to such event; and if any reclassification also
     results in a change in shares of Common Stock covered by Section 5.1.1 or
     5.1.2, then such adjustment shall be made pursuant to Sections 5.1.1, 5.1.2
     and this Section 5.1.3. The provisions of this Section 5.1.3 shall
     similarly apply to successive reclassifications, reorganizations, mergers
     or consolidations, sales or other transfers.

                    Section 5.1.4 This form of Warrant need not be changed
     because of any change pursuant to this Section, and Warrants issued after
     such change may state the same Exercise Price and the same number of
     Warrant Shares as are stated in the Warrant initially issued pursuant to
     this Agreement. The acceptance by any Holder of the issuance of new Warrant
     reflecting a required or permissive change shall not be deemed to waive any
     rights to an adjustment occurring after the Commencement Date or the
     computation thereof.

                    Section 5.1.5 In case of any consolidation of the Company
     with, or merger of the Company with, or merger of the Company into, another
     corporation (other than a consolidation or merger which does not result in
     any reclassification or change of the outstanding Common Stock), the
     corporation formed by such consolidation or merger shall execute and
     deliver to the Holder a replacement Warrant providing that the holder of
     each Warrant then outstanding or to be outstanding shall have the right
     thereafter (until the stated expiration of such Warrant) to receive, upon
     exercise of such Warrant the kind and amount of shares of stock and other
     securities and property receivable upon such consolidation or merger, by a
     holder of the number of shares of Common Stock of the Company for which
     such Warrant might have been exercised immediately prior to such
     consolidation, merger, sale or transfer. Such replacement Warrant shall
     provide for adjustments which shall be identical to the adjustments
     provided in Section 5. The above provision of this Section shall similarly
     apply to successive consolidations or mergers.

               Section 5.2 Elimination of Fractional Interests. The Company
     shall not be required to issue certificates representing fractions of
     shares of Common Stock or Warrants upon the exercise of the Warrant, nor
     shall it be required to issue scrip or pay cash in lieu of any fractional
     interests, it being the intent of the parties that all fractional interests
     shall be eliminated by rounding any fraction down to the nearest whole
     number of Warrants, shares of Common Stock or other securities, properties
     or rights.

     Section 6. Reservation and Listing.

               The Company shall at all times reserve and keep available out of
     its authorized shares of Common Stock, solely for the purpose of issuance
     upon exercise of the Warrant such number of shares of Common Stock or other
     securities, properties or rights as shall be issuable upon the exercise
     thereof. The Company covenants and agrees that, upon exercise of the
     Warrant and payment of the Exercise Price therefor, all shares of Common
     Stock and other securities issuable upon such exercise shall be duly and
     validly issued, fully paid and non-assessable and not subject to preemptive
     rights of any stockholder. As long as the Warrant shall be outstanding, the
     Company shall use its best efforts to cause all Warrant Shares issuable
     upon exercise of the Warrant to be listed (subject to official notice of
     issuance) on all securities exchanges (or, if applicable on the Nasdaq
     National Market, Capital Market, OTC Bulletin Board or any successor
     trading market) on which the Common Stock or the Public Warrants issued to
     the public in connection herewith may then be listed and/or quoted.


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<PAGE>

     Section 7. Certain Notice Requirements.

               Section 7.1 Holder's Right to Receive Notice. Nothing herein
     shall be construed as conferring upon the Holder the right to vote or
     consent as a stockholder for the election of directors or any other matter,
     or as having any rights whatsoever as a stockholder of the Company. If,
     however, at any time prior to the expiration of the Warrant and its
     exercise, any of the events described in Section 7.2 shall occur, then, in
     one or more of said events, the Company shall give written notice of such
     event at least fifteen (15) days prior to the date fixed as a record date
     or the date of closing the transfer books for the determination of the
     stockholders entitled to such dividend, distribution, conversion or
     exchange of securities or subscription rights, or entitled to vote on such
     proposed dissolution, liquidation, winding up or sale. Such notice shall
     specify such record date or the date of the closing of the transfer books,
     as the case may be. Notwithstanding the foregoing, the Company shall
     deliver to the Holder a copy of each notice given to the other stockholders
     of the Company at the same time and in the same manner that such notice is
     given to the stockholders.

               Section 7.2 Enumerated Events. The Company shall be required to
     give the notice described in this Section 7 upon one or more of the
     following events: (i) if the Company shall take a record of the holders of
     its shares of Common Stock for the purpose of entitling them to receive a
     dividend or distribution payable otherwise than in cash, or a cash dividend
     or distribution payable otherwise than out of retained earnings, as
     indicated by the accounting treatment of such dividend or distribution on
     the books of the Company, or (ii) the Company shall offer to all the
     holders of its Common Stock any additional shares of capital stock of the
     Company or securities convertible into or exchangeable for shares of
     capital stock of the Company, or any option, right or warrant to subscribe
     therefor, or (iii) a dissolution, liquidation or winding up of the Company
     (other than in connection with a consolidation or merger) or a sale of all
     or substantially all of its property, assets and business shall be proposed
     by the Company.

               Section 7.3 Change in Exercise Price. The Company shall, promptly
     after an event requiring a change in the Exercise Price pursuant to Section
     7 hereof, send notice to the Holder of such event and change (the "PRICE
     NOTICE"). The Price Notice shall describe the event causing the change and
     the method of calculating same and shall be certified as being true and
     accurate by the Company's President and Chief Financial Officer.

               Section 7.4 Transmittal of Notices. All notices, requests,
     consents and other communications under this Warrant shall be in writing
     and shall be deemed to have been duly made on the date of delivery if
     delivered personally or sent by overnight courier, with acknowledgement of
     receipt to the party to which notice is given, or on the fifth day after
     mailing if mailed to the party to whom notice is to be given, by registered
     or certified mail, return receipt requested, postage prepaid and properly
     addressed as follows: (i) if to the registered Holder of the Warrant, to
     the address of such Holder as shown on the books of the Company, or (ii) if
     to the Company, to its principal executive office.

     Section 8. Miscellaneous.

               Section 8.1 Amendments. The Company and the Underwriters may from
     time to time supplement or amend this Warrant without the approval of any
     of the Holders in order to cure any ambiguity, to correct or supplement any
     provision contained herein which may be defective or inconsistent with any
     other provisions herein, or to make any other provisions in regard to
     matters or questions arising hereunder which the Company and the
     Underwriters may deem necessary or desirable and which the Company and the
     Underwriters deem shall not


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<PAGE>

     adversely affect the interest of the Holders. All other modifications or
     amendments shall require the written consent of the party against whom
     enforcement of the modification or amendment is sought.

               Section 8.2 Headings. The headings contained herein are for the
     sole purpose of convenience of reference, and shall not in any way limit or
     affect the meaning or interpretation of any of the terms or provisions of
     this Warrant.

               Section 8.3 Entire Agreement. This Warrant (together with the
     other agreements and documents being delivered pursuant to or in connection
     with this Warrant) constitutes the entire agreement of the parties hereto
     with respect to the subject matter hereof, and supersedes all prior
     agreements and understandings of the parties, oral and written, with
     respect to the subject matter hereof.

               Section 8.4 Binding Effect. This Warrant shall inure solely to
     the benefit of and shall be binding upon, the Holder and the Company and
     their respective successors, legal representatives and assigns, and no
     other person shall have or be construed to have any legal or equitable
     right, remedy or claim under or in respect of or by virtue of this Warrant
     or any provisions herein contained.


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<PAGE>

               Section 8.5 Governing Law; Submission to Jurisdiction. This
     Warrant shall be governed by and construed and enforced in accordance with
     the laws of the State of New York, without giving effect to conflict of
     laws. The Company hereby agrees that any action, proceeding or claim
     against it arising out of, or relating in any way to this Warrant shall be
     brought and enforced in the courts of the State of New York or of the
     United States of America for the Southern District of New York, and
     irrevocably submits to such jurisdiction, which jurisdiction shall be
     exclusive. The Company hereby waives any objection to such exclusive
     jurisdiction and that such courts represent an inconvenient forum. Any
     process or summons to be served upon the Company may be served by
     transmitting a copy thereof by registered or certified mail, return receipt
     requested, postage prepaid, addressed to BIOPURE CORPORATION, 11 HURLEY
     STREET, CAMBRIDGE, MA 02141, ATTN: JANE KOBER, ESQ. Such mailing shall be
     deemed personal service and shall be legal and binding upon the Company in
     any action, proceeding or claim. The Company and the Holder, by acceptance
     hereof, agree that the prevailing party(ies) in any such action shall be
     entitled to recover from the other party(ies) all of its reasonable
     attorneys' fees and expenses relating to such action or proceeding and/or
     incurred in connection with the preparation therefor.

               Section 8.6 Waiver, Etc. The failure of the Company or the Holder
     to at any time enforce any of the provisions of this Warrant shall not be
     deemed or construed to be a waiver of any such provision, nor to in any way
     affect the validity of this Warrant or any provision hereof or the right of
     the Company or any Holder to thereafter enforce each and every provision of
     this Warrant. No waiver of any breach, non-compliance or non-fulfillment of
     any of the provisions of this Warrant shall be effective unless set forth
     in a written instrument executed by the party or parties against whom or
     which enforcement of such waiver is sought; and no waiver of any such
     breach, non-compliance or non-fulfillment shall be construed or deemed to
     be a waiver of any other or subsequent breach, non-compliance or
     non-fulfillment.

     IN WITNESS WHEREOF, the Company has caused this Warrant to be signed by its
duly authorized officer as of the __th day of January 2006.

                                        BIOPURE CORPORATION


                                        By:
                                            ------------------------------------

                   (Signature Page Underwriters' Warrant UW-3)


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<PAGE>

FORM TO BE USED TO EXERCISE WARRANT:

Biopure Corporation

Date: ______________, 200__

          The undersigned hereby elects irrevocably to exercise the within
Warrant and to purchase ____ Biopure Corporation and hereby makes payment of
$____________ (at the rate of $_________ per Share) in payment of the Exercise
Price pursuant thereto. Please issue the Share as to which this Warrant is
exercised in accordance with the instructions given below.

or

          The undersigned hereby elects irrevocably to exercise the within
Warrant and to purchase _________ Biopure Corporation by surrender of the
unexercised portion of the within Warrant (with a "Value" of $_______ based on a
"Market Price" of $__________.) Please issue the Warrant Shares as to which this
Warrant is exercised in accordance with the instructions given below.


                                        ----------------------------------------
                                        Signature

          NOTICE: THE SIGNATURE TO THIS FORM MUST CORRESPOND WITH THE NAME AS
WRITTEN UPON THE FACE OF THE WITHIN WARRANT IN EVERY PARTICULAR WITHOUT
ALTERATION OR ENLARGEMENT OR ANY CHANGE WHATSOEVER.

                   INSTRUCTIONS FOR REGISTRATION OF SECURITIES

Name ________________________________________________________
                     (Print in Block Letters)

Address ______________________________________________________


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<PAGE>

Form to be used to assign Warrant:

                                   ASSIGNMENT

          (To be executed by the registered Holder to effect a transfer of the
within Warrant):

          FOR VALUE RECEIVED,__________________________________ does hereby
sell, assign and transfer unto _______________________ the right to purchase
_______________________ of Biopure Corporation ("Company") evidenced by the
within Warrant and does hereby authorize the Company to transfer such right on
the books of the Company.

Dated: ___________________, 200_


                                        ---------------------------------------
                                        Signature


------------------------------------
Signature Guaranteed

          NOTICE: THE SIGNATURE TO THIS FORM MUST CORRESPOND WITH THE NAME AS
WRITTEN UPON THE FACE OF THE WITHIN WARRANT IN EVERY PARTICULAR WITHOUT
ALTERATION OR ENLARGEMENT OR ANY CHANGE WHATSOEVER, AND MUST BE GUARANTEED BY A
BANK, OTHER THAN A SAVINGS BANK, OR BY A TRUST COMPANY OR BY A FIRM HAVING
MEMBERSHIP ON A REGISTERED NATIONAL SECURITIES EXCHANGE.


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