Sudden deafness may be defined as a loss of at least 30 dB in three contiguous frequencies without definitive cause. We studied 32 cases of sudden deafness which were treated with low molecular weight dextran, steroid and vitamines. We calculated correcting rate which showed the percentage of hearing improvement based on initial hearing loss in cases with hearing loss of none affected side within 29dB. We used correcting rate as an indicator of prognosis. Right side was 14 cases, left side 15 cases and both side 3 cases. In audiogram, ascending type had favorable prognosis. In cases with dizziness and deaf patient on initial audiogram, prognosis was poor. There was difference of average in stapedial reflex threshold between two groups ; one having correcting rate above 50% and the other having it below 50%. This didn't have statistic significance.