Aptitude Regulatory News (APTD)

MICROGEN PLC

1 JULY 2011

BLOCK LISTING RETURN

Name of applicant: MICROGEN PLC

Name of scheme: MICROGEN PLC 1997 AND 1999 EXECUTIVE SHARE OPTION SCHEME

MICROGEN PLC 1996 SAVINGS RELATED SHARE OPTION SCHEME

Period of return: From: 1 JANUARY 2011 To: 30 JUNE 2011

Balance under scheme from previous returns:

MICROGEN PLC 1997 AND 1999 EXECUTIVE SHARE OPTION SCHEME - 68,000 ORDINARY SHARES OF 5P EACH

MICROGEN PLC 1996 SAVINGS RELATED SHARE OPTION SCHEME - 82,291 ORDINARY SHARES OF 5P EACH

MICROGEN PLC 1997 AND 1999 EXECUTIVE SHARE OPTION SCHEME - 745,000 ORDINARY SHARES OF 5P EACH

MICROGEN PLC 1996 SAVINGS RELATED SHARE OPTION SCHEME - 30,000 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: N/A

Number of securities issued/allotted under

scheme during period:

MICROGEN PLC 1997 AND 1999 EXECUTIVE SHARE OPTION SCHEME - 187,500 ORDINARY SHARES OF 5P EACH

MICROGEN PLC 1996 SAVINGS RELATED SHARE OPTION SCHEME - 0 ORDINARY SHARES OF 5P EACH

Balance under scheme not yet issued/allotted

at end of period

MICROGEN PLC 1997 AND 1999 EXECUTIVE SHARE OPTION SCHEME - 625,500 ORDINARY SHARES OF 5P EACH

MICROGEN PLC 1996 SAVINGS RELATED SHARE OPTION SCHEME - 112,291 ORDINARY SHARES OF 5P EACH

Number and class of securities originally

listed and the date of admission

MICROGEN PLC 1997 AND 1999 EXECUTIVE SHARE OPTION SCHEME - 800,000 ORDINARY SHARES OF 5P EACH

MICROGEN PLC 1996 SAVINGS RELATED SHARE OPTION SCHEME - 200,000 ORDINARY SHARES OF 5P EACH

15 APRIL 2005

MICROGEN PLC 1997 AND 1999 EXECUTIVE SHARE OPTION SCHEME - 745,000 ORDINARY SHARES OF 5P EACH

MICROGEN PLC 1996 SAVINGS RELATED SHARE OPTION SCHEME - 30,000 ORDINARY SHARES OF 5P EACH

27 JUNE 2008

Total number of securities in issue at the end

of the period

81,120,595 ORDINARY SHARES OF 5P EACH

Name of contact: PHILIP WOOD, DIRECTOR

Address of contact: OLD CHANGE HOUSE, 128 QUEEN VICTORIA STREET, LONDON, EC4V 4BJ

Telephone number of contact: 020 7496 8100

www.microgen.com