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                                    FORM 6-K
                     U.S. SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549


                        REPORT OF FOREIGN PRIVATE ISSUER
                   PURSUANT TO RULE 13A-16 OR 15D-16 UNDER THE
                         SECURITIES EXCHANGE ACT OF 1934


                            dated September 27, 2005


                         Commission File Number 0-51373


                        CHEMGENEX PHARMACEUTICALS LIMITED
                    (Exact Name as Specified in its Charter)

                                      N/A
                       (Translation of Registrant's Name)

                                  Pigdons Road
                                   Waurn Ponds
                            P.O. Box 1069, Grovedale
                             Victoria 3216 Australia
                    (Address of principal executive offices)


         Indicate by check mark whether the registrant files or will file annual
reports under cover of Form 20-F or Form 40-F.

         Form 20-F    X    Form 40-F
                    -----            -----

         Indicate by check mark if the registrant is submitting the Form 6-K in
paper as permitted by Regulation S-T Rule 101(b)(1):
- ----

         Indicate by check mark if the registrant is submitting the Form 6-K in
paper as permitted by Regulation S-T Rule 101(b)(7):
- ----

         Indicate by check mark whether by furnishing the information contained
in this Form, the registrant is also thereby furnishing the information to the
Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.

         Yes                        No  X
             ----                      ------

         If "Yes" is marked, indicate below the file number assigned to the
registrant in connection with Rule 12g3-2(b): Not applicable.

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                                   SIGNATURES

                  Pursuant to the requirements of the Securities Exchange Act of
1934, the registrant has duly caused the Report to be signed on its behalf by
the undersigned, thereunto duly authorized.


Date:  September 27, 2005



                                               CHEMGENEX PHARMACEUTICALS LIMITED



                                               By: /s/ Greg R. Collier
                                                   -----------------------------
                                                   Name:   Greg R. Collier
                                                   Title:  Managing Director







                                  EXHIBIT INDEX


Exhibit                    Description of Exhibit
- -------                    ----------------------

99.1                       Market announcement dated September 27, 2005