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               16 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            778,456    (1.46%)       211,807   (0.40%)
securities
(2) Derivatives         211,807    (0.40%)       518,856   (0.98%)
(other than
options)
(3) Options and               0    (0.00%)             0   (0.00%)
agreements to
purchase/sell
Total                   990,263    (1.86%)       730,663   (1.37%)


(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      1,925                12.9900
Purchase      167,897              13.0130
Purchase      91,310               12.9908
Purchase      5,000                13.0173
Purchase      10,000               12.9832
Sale          11,235               12.9825
Sale          1,596                12.9900
Sale          7,099                12.9852

(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          65,625                12.9843
CFD        LONG          120,754               13.013
CFD        LONG          31,788                12.9843
CFD        LONG          58,514                13.013
CFD        LONG          39,575                12.9843
CFD        LONG          72,835                13.013
CFD        LONG          33,989                12.9843
CFD        LONG          62,503                13.013
CFD        LONG          57,321                12.9843
CFD        LONG          105,394               13.013
CFD        Short         10,000                12.9832
CFD        Short         91,310                12.9908
CFD        Short         167,897               13.0130
CFD        Long          7,099                 12.9852
CFD        Long          1,596                 12.9900
CFD        Short         5,000                 13.0173


(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
                varying etc.      relates (Note 7)                                      5)


(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                         17 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