Sudden hearing loss(SHL) is defined as an abrupt onset of sensorineural hearing loss which developes over a period of hours or a few days without definitive cause. However, the etiology, treatment and prognosis of sudden hearing loss are controversial at present time. Authors observed 60 cases(57 patients) with sudden hearing loss who were admitted and treated with histamine phosphate or procaine during 4 year period (from May 1990 to May 1994) in our ENT department. They were evaluated by clinical & statistical analysis. The results were as follows : 1) Of the 60 cases, 13 cases(21.7%) had complete recovery, 12 cases(20.0%) had partial recovery, 7 cases(11.7%) had slight recovery and 28 cases(46.7%) had no response. 2) those patients who were treated within 2 weeks from onset had better improvement(p<0.01). 3) Those patients who had ascending or flat audiogram pattern had better improvement(p<0.05). 4) Histamine phoshate had as same treatment effect as the procaine(p>0.05). 5) The patients with tinnitus had better improvement than those with vertigo(p<0.001).