15 cases with sudden deafness were treatad by conservative therapies, and fair improvement of hearing was obtained in 2 cases, and slight improvement in one case. All of improved 3 cases were adequately administrated at least within 10 days after the attack of sudden deafness. The initial audiogram showed flat type in 2 cases and deaf type in one. In 2 cases with fair improvement of hearing, their prognosis were followed up during 2.5 or 1.5 years respectively. The improvement of hearing of both cases was lapid in initial stage, and then gradual. In one case, Bekesy audiograms revealed the transit from Jerger's type II to type I along with the fair improvement of hearing at 2.5 years after the onset of hearing loss. In other case, although initial fair improvement, Bekesy audiograms still showed Jerger's type II and standard audiometry revealed progressive deterioration on high frequencies, at 1.5 years after the onset of hearing loss.