• Autosomal dominant hereditary ataxias are heterogeneous groups of disorders in which cerebellar ataxia and pyramidal, extrapyramidal, and extraocular signs predominate. We studied a family with this type of disorder with evidence supporting a large-fiber sensory neuronopathy. Electrophysiologic, histologic, radiologic, and biochemical features were studied. Neuropathic features of some forms of autosomal dominant spinocerebellar degeneration are, therefore, believed to be due to a ganglioneuropathy similar to that described in Friedreich's ataxia.