In this report of a retrospective study of 144 cases of idiopathic sudden hearing loss, two important prognostic indicators appear: the elapsed time since the onset of symptoms and the degree of hearing loss. According to these indicators, the authors define three group of patients with a recovery rate of 65%: patients with a threshold hearing level of less than 40 dB, treated within two months of the onset of their hearing loss, patients with a threshold hearing level between 40 and 70 dB treated within one month and patients with a threshold hearing level of more than 70 dB treated within 7 days. Patients with a threshold hearing level of more than 70 dB, treated between 7 and 30 days, have only a partial recovery in 40%. The evaluation of efficacy of various treatment demonstrates a slight improvement of the hearing loss using steroids associated to vasodilatators, even if no significant difference is found between the different therapies. The normovolemic hemodilution and the treatment included mannitol seem to be ineffectual.