Objective To assess the prognostic factors associated with the sudden idiopathic sensorineural hearing loss, to predict the prognosis of patient with idiopthic sensorneural hearing loss precisely. Methods Eight hundreds and eighty two patients with idiopathic sudden sensorineural hearing loss were retrospectively reviewed during January 2006 to March 2007. Patients whose initial hearing threshold ≤40 dB were excluded. The patients with initial hearing threshold >40 dB were recruited, which was divided into six subgroups based on the patterns of audiogram ： downgrade audiogram subgroup, upgrade audiogram subgroup, flat audiogram subgroup, concave audiogram subgroup, profound audiogram subgroup and total deafness subgroup. Results Regarding to the relationship between the time point for initial intervention and the prognosis, better prognosis was obtained in patients whose initial intervention was within 3 days of the disease, good prognosis was achieved within 1 or 2 weeks of the disease, poor prognosis was noted beyond 2 weeks of this disease. Furthermore, comparison with the initial intervention within 3 week, 1 month and 1 month later, the prognosis among them was not statistical different. 97. 7% hearing recovery was achieved in the concave subgroup with the initial hearing threshold > 40 dB group. Comparison with the other subgroup （except total deafness subgroup）, the cure rate and recovery rate was 23.8% and 57.9% respectively in the profound subgroup. Poor prognosis was demonstrated in the total deafness subgroup and inefficacy rate was 67.4% in the total deafness subgroup. Comparison with patients without companying complications, the prognosis of patients with companying comphcations such as diabetes or high blood pressure has negative impact in hearing recovery. The age was correlated with the prognosis, elder had poor prognosis, patients more than 50 years old present with worse hearing than that less than 50 years old （H = 7. 851 ,P = 0. 0051 ）. Conclusions The initial intervention beyond 2 weeks had negative impact on the prognosis. The initial audiogram patterns and hearing threshold were both significant factors on the prognosis of idiopathic sudden sensorineural hearing loss. In addition, old patient had poor prognosis. The companying complications such as high blood pressure and diabetes had negative impact on the prognosis of idiopathic sudden hearing sensorineural loss.