PDMR

Costain Group PLC("Costain" or the "Company")

Transaction in shares by a Person Discharging Managerial Responsibility ("PDMR")

 Ordinary Shares of 50p each

The Company received notification on 23 August 2012 of the following transaction in its ordinary shares of 50p each ("Ordinary Shares") by James Morley, a Non-Executive Director of the Company.

On 23 August 2012, Mr Morley purchased (through Pershing Nominees) 4,000 Ordinary Shares at a price of 221.965p per share. The transaction was carried out in London.

This announcement is made following a notification made in accordance with Disclosure and Transparency Rule 3.1.2R.

23 August 2012

Enquiries:

Costain Group PLC Tel: 01628 842444Tracey Wood