Idiopathic sudden hearing loss(SHL) is defined as a sensorineural hearing loss which develops over a period of hours or a few days without definitive cause. However, the etiology, short term and long term prognosis and treatment of SHL have not been determined with precision. The purpose of this study is to seek the best modality of treatment and its prevention by clinical and statistical analysis of 121 patients, diagnosed as sudden sensorineural hearing loss from January 1977 to August 1985. The results were as follows : 1) The therapeutic results were 18 cases of complete recovery, 19 cases of partial recovery, 16 cases of slight recovery and 36 cases of no improvement. 2) Those patients who were treated within 2 weeks from onset revealed better recovery. 3) Prognosis was poor in cases of sudden hearing loss with vertigo. 4) Low frequency range hearing loss and flat hearing loss had good response. 5) Among various treatment, combined therapy with hypaque and heparin had a relatively good response. 6) Eighty-eight percent of the group that did recovery their hearing, did so within 2 weeks from the onset of therapy.