We describe a family showing dentatorubral-pallidoluysian atrophy. Three patients appeared through three successive generations and displayed a wide variety of clinical pictures. The male proband with onset in childhood showed progressive myoclonus epilepsy syndrome. The father experienced cerebellar ataxia, myoclonus, and mild dementia starting in middle age; the paternal grandmother had progressive symptoms of cerebellar ataxia, choreiform movements, and dementia, but neither myoclonus nor epilepsy in senescence. Neuropathologic examination of two patients, the proband and the paternal grandmother, revealed combined degeneration of the dentatorubral and pallidoluysian systems and obvious degeneration involving the striatum in the proband and the cerebellar cortex in the grandmother. The present study indicates that this disease can include many clinical and pathologic variants even in the same family.