In this article, we review 78 cases of Cogan's syndrome--18 from our institution and 60 from the English medical literature--and describe the clinical, laboratory, radiographic, and pathologic findings associated with this disorder. Patients with Cogan's syndrome should be examined by an ophthalmologist, otolaryngologist, and internist because, in addition to the eye and audiovestibular involvement, systemic manifestations are common. An elevated erythrocyte sedimentation rate, anemia, leukocytosis, and thrombocytosis are common but nonspecific laboratory abnormalities. Serious outcomes include deafness and, less frequently, vasculitis, aortic insufficiency, blindness, and death. Glucocorticoids seem to be effective therapy for active Cogan's syndrome. Aortic valve replacement and vascular bypass grafting are indicated in selected cases. The roles of cytotoxic-immunosuppressive agents and cochlear implantation remain to be clarified.