An open, multi-centre study was carried out in general practice to compare the efficacy, tolerability and acceptability of a neomycin/dexamethasone preparation administered by spray ('Otomize') and neomycin/polymyxin B/hydrocortisone administered as drops ('Otosporin') in the treatment of 187 patients with otitis externa. Patients were allocated at random to receive one or other preparation 3-times daily for 10 days irrespective of response and were followed up again 14 days after cessation of therapy. Assessments were made on entry and at Days 10 and 24 of the severity of erythema, swelling and debris. A global assessment of clinical outcome was made by the doctor on Day 10. There were no significant differences between the two groups at the start of treatment. Significant improvement occurred in both groups from Day 0 to Day 10 and from Day 10 to Day 24 in all symptoms, but no statistically significant differences were recorded between the two drugs. However, significantly more patients in the 'Otomize' group were rated as having a good clinical outcome by the physicians, and a highly significant number of patients, with previous experience of the use of ear drops, expressed a preference for the spray preparation. Few side-effects were reported by either treatment group, none necessitating discontinuation of therapy.