We have compared the clinical presentations and results of operative treatment in 86 patients with bilateral chronic otitis media with findings in 641 patients with unilateral disease. Concomitant conditions such as cleft palate, rhinitis and chronic adenotonsillitis were found significantly more frequently in those patients with bilateral chronic otitis media than in the patients with unilateral disease. Additionally, cholesteatomas in the cases in which both ears were involved were larger than in those cases which only one ear was involved. The overall results of surgery were similar in the bilateral and unilateral cases. The timing of operation in cases of bilateral chronic otitis media and the special problems of operation on an only hearing ear are discussed.