This paper seeks to investigate the impact of Section 18 of the Landlord and Tenant Act 1927 in settlement of dilapidation disputes. This is seen as a developing issue, in current economic conditions. The paper looks at the two limbs of Section 18, and offers practical advice to valuers on preparation of Section 18 valuations. By close analysis of the second limb followed by the first limb, the impact of the terms of the Act upon diminution in value used as a defence by tenants against landlord claims under dilapidations can be identified. This paper recognises that preparation of Section 18 valuations is a practical rather than a theoretical exercise and seeks to offer practical advice based upon the author's extensive experience of undertaking such work. The work is, however, mindful of the potential for litigation following such disputes and the role of the valuer in such an event.