Ciprofloxacin, a fluorinated quinolone with high efficacy against Pseudomonas aeruginosa, was used in the treatment of 10 consecutive patients with malignant external otitis. All patients had skull base osteomyelitis documented by nuclear and computed tomography (CT) scans. Dosages of 1.5 g of ciprofloxacin daily were used for a mean average of 10 weeks. All patients were considered cured with a minimum follow-up of 18 months after completion of therapy. A new classification of malignant external otitis (MEO) is presented.