A prospective study of otitis externa in the district of South Bedfordshire was undertaken between October 1990 and January 1991. Patients were referred untreated by general practitioners; self-referred patients with external otitis were also included. A detailed history was taken, the severity of the condition assessed, aural toilet performed, bacteriology swabs taken and the patient treated according to department protocol. 48 patients were included in the study; a similar number of age and sex-matched controls without otitis externa were randomly selected from the ENT outpatient clinics for comparison. Regular swimming emerged as a significant factor in the aetiology of otitis externa. The commonest organism cultured was Pseudomonas aeruginosa and this accounted for the most severe cases seen.