Rule 2.10 Announcement

Cambridge Antibody Tech Group PLC
13 June 2006


                                  ANNOUNCEMENT

FOR IMMEDIATE RELEASE

13 June 2006

                CAMBRIDGE ANTIBODY TECHNOLOGY GROUP PLC ("CAT")

                             RULE 2.10 ANNOUNCEMENT

CAT announces, in accordance with Rule 2.10 of the City Code on Takeovers and
Mergers, that subsequent to an issue of 200 ordinary shares under the CAT
Company Share Option Plan (OSCSOPO), its issued share capital as at 13 June
2006 comprises 53,206,393 ordinary shares of 10p each (including those
represented by American Depositary Shares) ("CAT Shares").

The ISIN reference number for the CAT Shares is GB0001662252 and for the
American Depositary Shares of CAT is US1321481079.

Enquiries:

Justin Hoskins (Company Secretary), CAT

Tel: [phone]

END


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