Since the risk of sensorineural hearing loss from persistent chronic otitis media and mastoiditis is greater than the risk to loss of labyrinthine function from carefully performed surgery, it is felt that the best treatment for chronic suppurative middle ear disease in an only-hearing ear is surgical removal of disease. Between the years 1961 to 1970 14 cases of chronic otitis media and mastoiditis in only-hearing ears were treated surgically at the Massachusetts Eye and Ear Infirmary. Five cases presented with resistant foul otorrhea, while five patients presented with increasing hearing loss and four with vertigo. The patients with hearing loss and vertigo were subjected to surgery at the earliest possible date. Wide-field surgical exposure of the mastoid and middle ear spaces with thorough removal of diseased tissue was carried out. Particular attention to avoid injury to the labyrinth, either directly or indirectly, must be kept in mind and it is recommended that surgery in only-hearing ears be performed by only the most experienced and capable otologic surgeon. All 14 ears have remained dry after surgery. Hearing was significantly improved in ten cases, while two were unchanged and two were made worse, as regards the conductive loss only. In all 14 cases postoperative discrimination scores were normal, so that even those cases that did not achieve serviceable hearing levels from surgery were able to use amplification. The results in this series confirm the feeling that carefully performed and timed surgery is effective in controlling chronic suppurative disease, while preserving function in only-hearing ears.