SCO CAPITAL PARTNERS LLC

                                        June 5, 2007

Board of Directors
Bioenvision, Inc.
345 Park Avenue, 41st Floor
New York, New York 10154

Bioenvision Board Members:

     In our initial letter to you dated May 29, 2007, we expressed our
disappointment and lack of support of the recent Genzyme offer. After further
consideration, we remain extremely concerned about the valuation and timing of
the transaction, and what appears to be a lack of a formal sale or auction
process. Further, we are extremely concerned about the appearance of conflicts
of interest among the board of directors and the holder of the Series A
Preferred Stock, namely Perseus-Soros Biopharmaceutical Fund L.P.
("Perseus-Soros"), and therefore whether the board has properly carried out its
fiduciary duties to all shareholders.

VALUATION & TIMING ISSUES

     It would appear, based on a series of communications, market conditions and
anticipated events, that the timing of this proposed sale and the proposed
valuation could not be worse. Why did the board approve this proposal when:

     o    Clofarabine appears to be readied for market approval in Adult AML in
          Europe and the US within the next six-to-twelve months. This is
          supported by communications by Bioenvision and Genzyme that multiple
          pivotal trials in Adult AML have shown "dramatic" complete response
          rates, in an indication with few good clinical treatments. The Adult
          AML market is several times larger than the pediatric ALL market,
          where the EMEA and FDA have already approved clofarabine (and
          presumably safety in children is of utmost importance). Management has
          disclosed that the regulatory process in Europe is on-track, and in
          fact better than expected.

     o    Bioenvision stock is trading near a four-year low, exacerbated by an
          ill-timed and extremely dilutive public equity offering announced on
          April 2, 2007 which drove the Bioenvision stock to new lows. The
          expressed purpose for the financing was to get the company to
          profitability and well into 2009.

     o    The valuation of less than $300 million after backing out in excess of
          $50 million in cash, appears to be less than one-time revenues of
          clofarabine in leukemia alone. And, this is based on Genzyme
          projections, not the

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          substantially higher projections of independent research analysts on
          Wall Street. Additionally, it gives no value to clofarabine's
          potential in a variety of other indications, such as myelodysplastic
          syndromes, non-Hodgkins lymphoma and bone marrow transplants where up
          to an additional 25 clinical trials are either planned or ongoing. The
          market for these assets is not one-time revenues, but rather in the
          range of four-to-eight times revenues.

     o    The presentation of clinical data on clofarabine at this week's
          American Society of Clinical Oncology (ASCO) meeting will likely
          further illustrate to the market the value of clofarabine in leukemia
          and a wide variety of other clinical indications.

     o    The biotechnology indices of the AMEX and NASDAQ have recently broke
          out to the upside of two-year trading ranges, perhaps signaling the
          beginning of a biotechnology bull market. This would coincide,
          serendipitously, with approvals of clofarabine in adult AML both in
          Europe and the US.

LACK OF A FORMAL SALES OR AUCTION PROCESS

     There was not sufficient time between the April financing and the
announcement of the Genzyme transaction to hire an investment bank, initiate a
formal sale or auction process, identify and contact alternative bidders on a
global scale, enter into confidentiality agreements, conduct a thorough due
diligence process, and then conclude a process whereby Genzyme was the final
bidder.

     o    We question whether, under Delaware Corporate Law, the board and
          management has properly fulfilled its fiduciary duties to all
          shareholders by not undertaking a formal sale or auction process.

     o    Additionally, including a termination fee in the merger agreement,
          particularly in the instance where a formal sales or auction process
          was not run, is likely to dissuade alternative bidders.

APPEARANCE OF CONFLICTS ON THE BOARD AND THE ROLE OF PERSEUS-SOROS

     It appears from the SEC-filed merger agreement that Perseus-Soros and its
employees and board designees have already entered into an agreement to support
the Genzyme tender offer. We question whether the directors affiliated with
Perseus-Soros were conflicted when they approved this transaction at the board
level:

     o    Given the lack of a formal sale or auction process, and the fact that
          Perseus-Soros and its employees and designees have agreed to the
          proposed offer, it would appear that Perseus-Soros may have simply
          grown tired of its investment in Bioenvision and brokered a "quick
          sale" to Genzyme, a corporate entity with which Perseus-Soros has had
          previous business dealings

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          and for which individuals at Perseus-Soros have previously acted as
          investment bankers.

     o    Perseus-Soros' cost basis in Bioenvision is likely to be substantially
          lower than most common stock shareholders, and while a quick sale at
          $5.60 may be deemed as a satisfactory outcome for themselves, it would
          seem to represent a transaction where the best interests of all equity
          shareholders was not fully considered.

     We have been inundated with calls from institutional and individual
shareholders that vehemently oppose the Genzyme offer on the grounds that it is
inadequate, and express the same reservations concerning timing and the lack of
a formal auction process. Clearly, with over 20 million shares trading above the
$5.60 offer price since its announcement, the market does not support this
transaction. If Perseus-Soros wants an exit strategy, they should sell their
shares to other investors rather than orchestrating a poorly-timed and
inadequately priced tender offer.

                                        Sincerely,


                                        /s/ Steven H. Rouhandeh
                                        ----------------------------------------
                                        Steven H. Rouhandeh
                                        Chairman

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                    TELEPHONE: 212-554-4158 FAX: 212-554-4058