Holding(s) in Company

Cambridge Antibody Tech Group PLC
22 December 2004

                                  SCHEDULE 10

                   NOTIFICATION OF MAJOR INTERESTS IN SHARES


1)   Name of company

Cambridge Antibody Technology Group plc


2)   Name of shareholder having a major interest

OrbiMed Advisors LLC


3)   Please state whether notification indicates that it is in respect of
     holding of the shareholder named in 2 above or in respect of a
     non-beneficial interest or in the case of an individual holder if it is a
     holding of that person's spouse or children under the age of 18


As in 2 above


4)   Name of the registered holder(s) and, if more than one holder, the
     number of shares held by each of them


OrbiMed Advisors LLC


5)   Number of shares/amount of stock acquired

Nil


6)   Percentage of issued class

Nil


7)   Number of shares/amount of stock disposed

537,000 Ordinary Shares and
113,000 American Depositary Receipts


8)   Percentage of issued class

1.263%


9)   Class of security

Ordinary 10 pence shares


10)  Date of transaction

20 December 2004


11)  Date company informed

21 December 2004


12)  Total holding following this notification

2,768,000 of which
2,417,000 are held in the form of ordinary 10 pence shares and
351,000 are held in the form of American Depositary Receipts



13)  Total percentage holding of issued class following this notification

5.38%


14)  Any additional information

OrbiMed Advisors LLC has investment management discretion over the following
securities:


Caduceus Capital Master Fund Limited
Caduceus Capital II L.P.
UBS Eucalyptus Fund L.L.C.
UBS Eucalyptus Fund Ltd
HFR SHC Aggressive Master Trust
Knightsbridge Post Venture IV L.P.
Knightsbridge Integrated Holdings, V, L.P.
Knightsbridge Netherlands II L.P.
Knightsbridge Integrated Holdings IV Post Venture LP
Knightsbridge Post Venture III LP
Knightsbridge Netherland I LP
Knightsbridge Netherlands III LP
Knightsbridge Integrated Holdings II Limited
Knightsbridge Venture Capital VI LP
Knightsbridge Venture Capital IV L.P.
Knightsbridge Venture Capital III LP
Topanga XIII Inc.
Caduceus Capital III, L.P.


15)  Name of contact and telephone number for queries

Justin Hoskins 01223 898589


16)  Name and signature of authorised company official responsible for
     making this notification


Diane Mellett, Company Secretary



Date of notification: 22 December 2004





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