Susac's syndromeis a rare disorder characterized by the triad of microangiopathy of the brain and retina with hearing loss. More than 50 affected individuals have been reported worldwide, all Caucasians. Weherein identify the first Japanese patient with Susac's syndrome. A 36-yearold mandeveloped recurrent subacute encephalopathy, bilateral sensorineural hearing loss, and retinal arteriolar occlusions, caused by microangiopathy from a year previously. T2-weighted MRIshowed multiple high-signal lesions predominantly in the periventricular white matter. During the exacerbated phase both high-dose intravenous methylprednisolone and oral prednisone therapy produced beneficial effects. He showed definite remission within 2 years from the disease onset. (Internal Medicine 40: 135-139, 2001)