Nerve conduction studies have been performed in 19 subject with hereditary spinocerebellar degenerations other than Friedreich ataxia. Clinically, they may be classified as olivopontocerebellar atrophy or cerebello-olivary degeneration. In 9 patients, sensory conduction was abnormal, and in the whole group there was a significant impairment of sensory conduction and mild slowing of motor conduction in the lateral popliteal nerve. Sural nerve biopsies were performed on 5 patients. In 3 cases there was a mild to moderate reduction of myelinated fibers of all diameters; unmyelinated fibers were normal. In 1 patient from a kindred with a spinocerebellar degeneration in which the inheritance was autosomal dominant, neuropathological findings at autopsy confirmed the clinical diagnosis of the Menzel type of olivopontocerebellar atrophy; there was a degeneration of dorsal root ganglion and anterior horn cells as well as of myelinated fibers of all diameters in the sural nerve.