From a total of 720 patients with acute deafness, 85 patients suffered from unilateral deafness with a hearing loss of at least 80 dB in the speech frequency range. Under conservative therapy in 58 patients, there was an improvement in hearing in 19 cases and a return to normal in 6 patients. In 27 patients, the clinical history was suggestive of a possible tympanic membrane rupture, which was confirmed by tympanoscopy in 5 cases. On 5 other occasions, the intraoperative findings were highly suggestive of tympanic membrane rupture. In each case, a membranoplasty was performed. The results of operative therapy tended to give better results than conservative therapy. The presence of concomitant vestibular disorders did not influence the results of treatment in either group. The results of the study show, that apart from tympanoscopy, there are no other diagnostic criteria to recognize a membrane rupture. Typical case histories demonstrate that tympanoscopy can be useful diagnostic and therapeutic measure in cases of therapy-resistant deafness.