A standardized, semi-structured interview for examining and recording the mental state in elderly subjects is described. It allows the classification of patients by symptom profile and can demonstrate changes in that profile over time. It is believed that good reliability is demonstrated between psychiatric raters both for psychiatric diagnosis made on the basis of the schedule findings and for individual items. The Geriatric Mental State Schedule (GMS) consists mainly of items from the eighth edition of the PSE (Wing et al. 1967), together with additional items from the PSS (Spitzer et al. 1964), and extra sections dealing with disorientation and other cognitive abnormalities. Modifications have been introduced to facilitate interviewing elderly subjects.