The authors report on a case of Cogan's syndrome pointing out that hearing loss is due both to cochlear lesions from likely immunitary origin as well as to widespread alterations of auditory central nervous structures. This interpretation allows to explain the apparent discrepancy of the found clinical and instrumental data. From a therapeutic point of view, the authors assert the necessity of an early corticosteroid therapy to obtain some appreciable result. Anyway, they point out how prognosis for auditory function in Cogan's syndrome is often very poor.