We report the results of a retrospective study of all computerised tomography (CT) brain scans of adult patients carried out over a 10-week period, based on radiological and clinical records. The commonest scan results were normal (51%) and stroke (26%), with an overall diagnostic accuracy of 43/80 (54%). On the basis of a retrospective blind survey by a neurologist, 42% of scans were thought not to be indicated. The results indicate the need for: guidelines on the use of CT scanning in stroke. Emphasis of current guidelines on the use of CT scanning in head injury. Neurological assessment of some suspected diagnoses before scanning.