Blocklisting - Interim Review

MICROGEN PLC

2 JULY 2008

                             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 2008 To: 30 JUNE 2008

Balance under scheme from previous return:

MICROGEN PLC 1997 AND 1999 EXECUTIVE SHARE OPTION SCHEME - 365,500 ORDINARY
SHARES OF 5P EACH

MICROGEN PLC 1996 SAVINGS RELATED SHARE OPTION SCHEME - 82,291 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 - 20,000 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 - 345,500 ORDINARY
SHARES OF 5P EACH

MICROGEN PLC 1996 SAVINGS RELATED SHARE OPTION SCHEME - 82,291 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

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

102,899,776 ORDINARY SHARES OF 5P EACH

Name of contact: PHILIP WOOD

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

Telephone number of contact: 01252 772 312

www.microgen.com