Seventeen patients with malignant external otitis were treated with oral ofloxacin. Their mean age was 69 years. Seven of the patients were diabetic. Pseudomonas aeruginosa, sensitive to ofloxacin (Kirby-Bauer method, inhibition zone greater than or equal to 22 mm), was isolated from the external auditory canal in all patients. Ofloxacin (200 mg b.i.d.) was given to the patients for 12 to 39 days. Two patients also received additional parenteral antibiotic therapy. Subjective and objective improvement occurred in all patients during treatment, and complete resolution was documented in all patients, with one exception. Only one patient suffered recurrence 2 weeks after discontinuation of antimicrobial therapy. The results of our study suggest that oral ofloxacin is an effective treatment for malignant external otitis caused by Pseudomonas aeruginosa.