Twenty-five patients with suspected perilymph fistula were evaluated. Eleven of them have positive history for perilymph fistula ; blunt head trauma, physical exertion, severe cough, barotrauma, and noise trauma. Fourteen of them had negative history, and were not responsive to conservative treatment for sudden hearing loss. The fistulas were found in 6 cases at oval window, and 3 cases at round window. Positive findings for fistula were fibrous bands, mucosal cracking, and lymph engorgement. In 9 fistula group, 3 cases had complete recovery in bone-conducting threshold. 1 case had slight recovery. In 16 non-fistula group, only 3 cases had complete recovery. 3 cases operated before 7 days of the onset of symptoms had complete recovery, whereas 22 cases operated after 7 days of the onset had recovery rate of 23%. There were over-all 89% improvement of labyrinthine symptoms. There were no differences between fistula and non-fistula group.