Aptitude Regulatory News (APTD)

MICROGEN PLC

27 SEPTEMBER 2010

BLOCK LISTING RETURN

Name of applicant: MICROGEN PLC

Name of scheme: MICROGEN PLC PERFORMANCE SHARE PLAN 2006

MICROGEN PLC COMPANY SHARE OPTION PLAN 2006

Period of return: From: 7 MARCH 2010 To: 24 SEPTEMBER 2010

Balance under scheme from previous return:

MICROGEN PLC PERFORMANCE SHARE PLAN 2006 - 60,375 ORDINARY SHARES OF 5P EACH

MICROGEN PLC COMPANY SHARE OPTION PLAN 2006 - 142,001 ORDINARY SHARES OF 5P EACH

The amount by which the block scheme has been increased, if the scheme has been increased since the date of the last return:

MICROGEN PLC PERFORMANCE SHARE PLAN 2006 - 650,000 ORDINARY SHARES OF 5P EACH

MICROGEN PLC COMPANY SHARE OPTION PLAN 2006 - 350,000 ORDINARY SHARES OF 5P EACH

Number of securities issued/allotted under scheme during period:

MICROGEN PLC PERFORMANCE SHARE PLAN 2006 - 275,807 ORDINARY SHARES OF 5P EACH

MICROGEN PLC COMPANY SHARE OPTION PLAN 2006 -91,339 ORDINARY SHARES OF 5P EACH

Balance under scheme not yet issued/allotted at end of period

MICROGEN PLC PERFORMANCE SHARE PLAN 2006 - 434,568 ORDINARY SHARES OF 5P EACH

MICROGEN PLC COMPANY SHARE OPTION PLAN 2006 - 400,662 ORDINARY SHARES OF 5P EACH

Number and class of securities originally listed and the date of admission

MICROGEN PLC PERFORMANCE SHARE PLAN 2006 - 127,460 ORDINARY SHARES OF 5P EACH - 7 SEPTEMBER 2009

MICROGEN PLC COMPANY SHARE OPTION PLAN 2006 - 142,001 ORDINARY SHARES OF 5P EACH - 7 SEPTEMBER 2009

MICROGEN PLC PERFORMANCE SHARE PLAN 2006 - 650,000 ORDINARY SHARES OF 5P EACH - 24 SEPTEMBER 2010

MICROGEN PLC COMPANY SHARE OPTION PLAN 2006 - 350,000 ORDINARY SHARES OF 5P EACH - 24 SEPTEMBER 2010

Total number of securities in issue at the end of the period

80,454,584 ORDINARY SHARES OF 5P EACH

Name of contact: ANJUM SIDDIQI, COMPANY SECRETARY

Address of contact: FLEET HOUSE, 3 FLEETWOOD PARK, BARLEY WAY, HANTS, GU51 2QJ

Telephone number of contact: 01252 772 326

www.microgen.com