Rule 8.3 - CAMBRIDGE ANTIBODY TECHNOLOGY GROUP PLC

FORM 8.3

    DEALINGS BY PERSONS WITH INTERESTS IN SECURITIES REPRESENTING 1% OR MORE
              (Rule 8.3 of the City Code on Takeovers and Mergers)


1.   KEY INFORMATION

Name of person dealing        BARCLAYS PLC
(Note 1)
Company dealt in              CAMBRIDGE ANTIBODY TECHNOLOGY GROUP PLC
Class of relevant security    ORD GBP 0.10
to which the dealings being
disclosed relate (Note 2)
Date of dealing               15 MAY 2006

2.   INTERESTS, SHORT POSITIONS AND RIGHTS TO SUBSCRIBE

(a)  Interests and short positions (following dealing) in the class of relevant
security dealt in (Note 3)

                            Long                    Short

                      Number       (%)        Number       (%)

(1) Relevant            522,254    (0.98%)       475,732   (0.89%)
securities
(2) Derivatives         475,732    (0.89%)     1,165,567   (2.19%)
(other than
options)
(3) Options and               0    (0.00%)             0   (0.00%)
agreements to
purchase/sell

Total                   997,986    (1.88%)     1,641,299   (3.09%)


(b)  Interests and short positions in relevant securities of the company, other
     than the class dealt in (Note 3)

Class of                    Long                     Short
relevant
security:

                  Number                    Number
                                    (%)                       (%)
(1) Relevant
securities

(2) Derivatives
(other than
options)

(3) Options and
agreements to
purchase/sell

Total


(c)  Rights to subscribe (Note 3)

Class of relevant security:   Details



3.   DEALINGS (Note 4)

(a)  Purchases and sales

Purchase/sale Number of Securities Price per unit
                                   (GBP)
Purchase      39,616               12.9899
Purchase      20,100               12.8588
Purchase      93                   12.9870
Purchase      50,000               12.9192
Sale          6,600                12.9750
Sale          20,248               12.9658

(b)  Derivatives transactions (other than options)

Product    Long/Short    Number of Securities  Price Per
name,      (Note 6)      (Note 7)              Unit (GBP)
e.g. CFD
CFD        Long          20,248                12.9658
CFD        Short         20,100                12.8588
CFD        Short         39,616                12.9899
CFD        Short         93                    12.9870
CFD        Short         55,084                12.9859
CFD        Long          28494                 12.9834
CFD        Long          13805                 12.9834
CFD        Long          17185                 12.9834
CFD        Long          14747                 12.9834
CFD        Long          24869                 12.9834

(c)  Options transactions in respect of existing securities

(i)  Writing, selling, purchasing or varying

Product name,   Writing,          Number of          Exercise  Type, e.g.      Expiry   Option money
e.g. call       selling,          securities to      price     American,       date     paid/received
option          purchasing,       which the option             European etc.            per unit (Note 5)
                varying etc.      relates (Note 7)


(ii) Exercising

Product name, e.g.  Number of           Exercise price per
call option         securities          unit (Note 5)




(d)  Other dealings (including new securities) (Note 4)


Nature of transaction Details           Price per unit
(Note 8)                                (if applicable)
                                        (Note 5)



4.   OTHER INFORMATION

Agreements, arrangements or understandings relating to options or derivatives


Full details of any agreement, arrangement or understanding between the
person disclosing and any other person relating to the voting rights of
any relevant securities under any option referred to on this form or
relating to the voting rights or future acquisition or disposal of any
relevant securities to which any derivative referred to on this form is
referenced.  If none, this should be stated.





Is a Supplemental Form 8 attached? (Note 9)                 NO


Date of disclosure                         16 MAY 2006
Contact name                               BARCLAYS COMPLIANCE
Telephone number                           0207 116 2913
If a connected EFM, name of
offeree/offeror with which connected
If a connected EFM, state nature of
connection (Note 10)


Notes

The Notes on Form 8.3 can be viewed on the Takeover Panel's website at
www.thetakeoverpanel.org.uk