OBJECTIVE To describe the efficacy of long-term oral steroids in idiopathic sudden sensorineural hearing loss (ISSHL), and to explore potential prognosis factors, the relationship of hearing recovery outcome, and the recovery time-course in ISSHL. METHODS In this retrospective study, we analyzed 215 cases diagnosed with idiopathic unilateral sudden deafness between January 2003 and December 2012 at a regional hospital in southern Taiwan. All of them received oral steroid therapy and were followed for at least 3 months. RESULTS Young age, the presence of no other disease (diabetes, hypertension, or cardiovascular disease), treatment within 7 days of the onset of ISSHL, mild hearing loss, and audiograms with ascending curves had a statistically significant better hearing recovery. The average pure-tone audiometry (PTA) was 67.8±23.9 dB initially, and was improved between one month (51.6±28.7 dB) and 2 months post treatment (49.7±28.6 dB). The average last-visit PTA was 49.9±29.2 dB. CONCLUSIONS Approximately one third of patients had full recovery in hearing, one third had partial recovery, and approximately one third did not recover from hearing loss. In addition, the hearing level remained relatively stable following 2 months of treatment. More than 2 months of oral steroid therapy for ISSHL is not recommended because no additional benefits were evidenced.