About concerning factors for the recovery of sudden deafness, various studies have been done, but there are still many unknown things. On 93 cases(102 ears) of sudden deafness who were able to be got follow-up after hospitalization more than 2 weeks and treatment until the fixed hearing at Audiology Clinic of PNUH from Jan. 1976 to Dec. 1986, the factors related to the prognosis were studied. Data were statistically examined using test and analysis of variance etc. And the following results were obtained : 1) The shorter the duration from onset to initiation of treatment is, the better prognosis is. And there was statistical significance between the recovery of hearing within 7 days group and that above 15 days group(p<0.05). 2) The more severe hearing loss is, the poorer prognosis is in all frequencies. Especially the prognosis was poor in cases above 70 dB of mean hearing threshold than that below 70 dB. 3) The hearing loss showed more improvement in low and middle frequencies than that of high one, but there was no statistical significance in hearing recovery between each frequency. 4) The hearing recovery as better in the age group below 49 than that of over 50 in all frequencies(p<0.05), but there was no statistical difference in hearing recovery according to sex. 5) The hearing recovery was poor in cases with vertigo than those without vertigo(p<0.05), but there was no change in hearing recovery whether tinnitus is preset or not. 6) The audiogram type was 40.2% in flat, 26.5% in profound, 18.6% in low-frequency, 14.7% in high-frequency type in order. There was no statistical difference in hearing recovery according to type of audiogram except profound type.