Exhibit 10.27

                    Amendment to the Co-Development Agreement
              between Bioenvision, Inc. and Southern Research Institute


WHEREAS Southern Research Institute ("SRI") and Eurobiotech Group, Inc. (now
Bioenvision, Inc., through a 100% equity purchase) (hereinafter "Bioenvision"),
had executed a Co-Development Agreement on August 31, 1998 for the commercial
development of Clofarabine, and

WHEREAS the parties to that Agreement now wish to amend the Agreement.

IT IS HEREBY AGREED THAT the following amendments shall apply:

1.      In Article 1. DEFINITIONS, Clause H replaces the term Gross Sales
        Revenue and shall now read:

        H.     Net Sales Revenue means the gross amount recognized by a party or
               its  Affiliates or  sublicensees  for the sale of  Clofarabine or
               other  Product(s)  through  normal   distribution   channels  (as
               determined  by  generally  accepted  accounting   principles  and
               industry  practices),  less any  deductions for value added taxes
               incurred,  and not recovered by such party or the equivalent,  or
               trade discounts,  or returns, or such deductions that may be made
               from the sale price in the Territory.

               In Article 1.  DEFINITIONS,  Clause F and G,  substitute the term
               "Gross Sales Revenue" with the term "Net Sales Revenue."

               In Article 1.  DEFINITIONS, Clause L shall now read:

               L.   Net Income means the  difference  between Net Sales  Revenue
                    and the sum of Cost of  Goods  sold and  Operating  Expenses
                    (Appendix  IV) with all  royalties,  local taxes,  corporate
                    income  taxes,  foreign  taxes,  and  accrued  start-up  and
                    development costs treated as excluded costs.

In Article 1.  DEFINITIONS, Clause F delete the term "SRI" and replace with the
term "all."

2.      In Article 10. DILIGENCE, Clause B shall now read:

        B.     Retention of rights by Bioenvision is contingent  upon submission
               of a NDA to the FDA  within  six years of the  effective  date of
               this  Agreement,  provided that such date is consistent  with the
               regulatory  strategy  agreed upon by Bioenvision and SRI with the
               FDA.  The  parties  acknowledge  and agree  that SRI may agree to
               extend  the  deadline  for  submission  of a NDA to the FDA  upon
               request by Bioenvision, which agreement shall not be unreasonably
               withheld,  so long as Bioenvision continues to use all reasonable
               efforts to  complete  the filing in due form as  promptly  and as
               reasonably practicable during such extended period.

3.       The following shall be an addendum to Article 5A:

For the purposes of the Co-Development Agreement between Bioenvision, Inc. and
Ilex Oncology, Inc. (hereinafter "ILEX") executed on March 8, 2001 (hereinafter
"Bioenvision-ILEX Agreement") in which ILEX shall be considered a sublicensee of
Bioenvision, and only for such purposes, it is agreed that the royalties
received by Bioenvision from ILEX, its Affiliates or sublicensees for the sales
of Clofarabine or any Product in the Field and in the Territory shall be divided
between SRI and Bioenvision according to the following table:


<PAGE>


         Annual Net Sales            Total Royalty            % Total Royalty
        Revenue ($ Million)      (% Net Sales Revenue)             to SRI
      -------------------------------------------------------------------------

           0  -     30                   8.75                      71.429
          >30  -   100                   11.25                     55.556
         >100  -   200                   12.50                     56.000
         >200  -   500                   15.00                     50.000
                   500+                  18.75                     53.333

Bioenvision will pay SRI its percentage of the royalties as per above within
five (5) business days of receipt by Bioenvision from ILEX of the royalty
payments due Bioenvision in accordance with Article 8.2 of the Bioenvision-ILEX
Agreement by electronic wire transfer of funds in US dollars as per above to the
following account:

        AmSouth Bank
        Account No. 01389483
        Routing No. 062000019
        For Intellectual Property

The milestone payments paid by ILEX to Bioenvision in Article 3 of the
Bioenvision-ILEX Agreement shall be split 50/50 between Bioenvision and SRI.
Additionally, SRI shall receive 50% of the US$1.35 million closing payment to
Bioenvision from ILEX, referred to in Article 3.3 of the Bioenvision-ILEX
Agreement. All payments due SRI under Article 3 of the Bioenvision-ILEX
Agreement shall be made within five (5) business days of receipt by Bioenvision
from ILEX by electronic wire transfer of funds in US$ to the account designated
above.

4.      In Article 4. LICENSE FEE AND RESEARCH AND DEVELOPMENT FUNDING, Clause D
        shall now read:

               Upon successful completion of Phase II clinical trials SRI and
               Bioenvision may jointly pay the costs of Phase III clinical
               trials and further Product development. If SRI shall not jointly
               fund the cost of such trials Bioenvision may pay the costs in
               full after paying a non-refundable option fee of $750,000 within
               60 days of completion and evaluation of Phase II trials or 60
               days from the commencement of Phase III trials, whichever is
               earlier. Completion and evaluation, for this purpose, shall mean
               the date on which all patients will have finished treatment as
               defined in the protocol for the pivotal Phase II clinical trial.
               If Bioenvision and SRI jointly develop the Product in Phase III
               trials no option fee shall be payable by Bioenvision.

In Article 4, Clause E shall now read:

        E.     Bioenvision  has  issued  to SRI one or more  share  certificates
               evidencing,  in the  aggregate,  100,000  shares  of  Bioenvision
               common  stock.  The  share   certificate(s)   were  issued  in  a
               transaction  not involving a public  offering and,  consequently,
               bear a restrictive  legend in accordance  with  requirements  and
               practice  under  The  Securities  Act of 1933,  as  amended.  SRI
               desires   to  have   the   restrictive   legend   on  the   share
               certificate(s) removed.  Bioenvision covenants and agrees to take
               all necessary  steps to cause new share  certificates  evidencing
               those shares,  without the  restrictive  legend,  to be issued in
               exchange for the share  certificates  containing the  restrictive
               legend, promptly and, in any event, within 15 business days after
               SRI  surrenders  the  existing  share  certificates,  along  with
               customary  stockholder  representation  letters  and  opinions of
               counsel  (relating to the satisfaction of the applicable  holding
               period  and other  requirements  under  Rule  144,  etc.) for the
               removal of the  restrictive  legend in compliance with applicable
               securities laws.

5. In Article 12, PATENT PROSECUTION, Clause B shall now read

        B.     Bioenvision  shall  bear all  patenting  expenses  related to the
               filing,  prosecution or maintenance of all Patent and Improvement
               licensed  hereunder  in whole or in  part.


<PAGE>


               Payments owed to SRI shall be payable  within five (5) days after
               the end of the  month in which  the  invoice(s)  for  payment  is
               received by Bioenvision.

6.      In Article 8. PAYMENTS AND REPORTS, Clause C shall now read:

        C.     All payments from Bioenvision to SRI shall be made by electronic
               wire transfer of funds in US dollars to the account referred to
               in Article 5A.

In Article 8, Clause H shall now read:

        H.     Bioenvision  shall  deliver  to SRI within  forty-five  (45) days
               after the end of each calendar quarter a report, certified by the
               chief financial  officer (or equivalent) of Bioenvision,  setting
               forth in reasonable  detail the  calculation of SRI payments made
               during the quarter and for each calendar quarter, including gross
               sales, net sales,  value added taxes,  number of units sold, unit
               price,   royalties   by  net  sales  range  and  the  like  on  a
               country-by-country  basis,  and  include a  sufficient  basis for
               understanding  the  methodology  and  rationale  for  calculating
               profit sharing as per Appendix IV, by Bioenvision,  sublicencees,
               joint ventures and their affiliates.

In Article 8, add Clause K

        K.     Within  fifteen (15) days of  execution  of the  Bioenvision-ILEX
               Agreement,  Bioenvision  shall  pay to SRI all  past  due  patent
               prosecution costs in the sum of $US36,682.75  pursuant to Article
               12.

7.      Appendix I, attached hereto, is amended to update the list of patents
        and/or patent applications referred to in Article 1, Clause M.

8.      Appendix IV shall now read:

H Excludes all royalties.

I Excludes all royalties, local taxes, corporate income taxes, foreign taxes,
and accrued start-up and development costs.

In Appendix IV, substitute the term "Net Sales Revenue" for the term "Gross
Sales Revenue."

9.      The following shall be added as Article 34.

                             34. SURVIVAL OF OBLIGATIONS

In the event of any termination of this Agreement, all obligations of
Bioenvision and SRI existing prior to termination and all obligations, whether
known or unknown at the time of termination, stemming from the act or omissions
of a given Party while this Agreement was in force and effect, shall remain an
obligation of the given Party until discharged. Article(s) 5, 6, 7, 9, 15, 18,
19, 21, 22 and 36 as well as any other provisions to the extent required for the
full observation and performance of the foregoing Articles or which by their
nature are intended to survive such termination, shall survive the termination
of this Agreement and continue to be enforceable.

10.     Article 34. NOTICE is renumbered Article 35.

11.     In Article 6, COMMERCIALIZATION STAGE, Clause A, substitute the term
        "Net Sales Revenue" for the term "Gross Sales Revenue.

12.     In Article 35, EXECUTION is renumbered as Article 36.


<PAGE>


TN WITNESS WHEREOF, the parties have caused this amendment to be executed by
their duly authorized officers on the respective dates hereinafter set forth,
said amendment to be effective as of March 12th, 2001.

Bioenvision, Inc.                             Southern Research Institute

Signature /s/ C.B. Wood                       Signature /s/ Randall C. Shealy
          -------------                                 -----------------------

Print Name C.B. Wood                          Print Name Randall C. Shealy
           ------------                                  ------------------

Date  March 12, 2001                          Date  March 12, 2001
      ---------------                               ---------------