Transaction in Own Shares

25 July 2012

Microgen plc ("the Company")

Transaction in own shares

Pursuant to the authority given to the Company by shareholders at the AGM, the Company announces that it has purchased ordinary shares of 5p each as follows:

Date of purchase: 24 July 2012

Number of ordinary shares purchased: 50,000

Highest price paid and lowest price paid: 120.0p

The purchase represented an average price of 120.0p per share.

The purchased shares will be cancelled. Following this purchase, the total number of voting rights in Microgen plc is 81,628,378.

Enquiries:

Philip Wood, Group Finance Director

Tel.: 020 7496 8100

www.microgen.com