We used computed tomography (CT) to evaluate 44 patients who had undergone stapedectomy with insertion of a prosthesis. Several patients had poor surgical results, including recurrent conductive hearing loss, vertigo, and sensorineural hearing loss. Conductive hearing loss occurring immediately after the procedure was most often caused by anatomic limitations or surgical technique. Causes of delayed or recurrent conductive hearing loss included reparative granuloma formation, incus necrosis (at the attachment of the wire), prosthesis subluxation (most often posterior), and regrowth of otosclerosis, which occasionally is further complicated by incus dislocation. We found that CT is often diagnostic when these complications occur. Immediate sensorineural hearing loss or vertigo can be self-limited if caused by serous labyrinthitis. When delayed, these symptoms may be due to perilymph fistula. If caused by the latter, CT may not yield abnormal findings unless subluxation of the prosthesis into the vestibule has occurred.