We describe two families (including one previously reported) in which cerebellar or spinocerebellar ataxia, hypogonadotropic hypogonadism, and choroidal dystrophy result from abnormal function of an autosomal recessive gene. Review of the literature adds one other family with this disorder. These three examples confirm the existence of this traid as a specific, pleiotropic, single-gene syndrome. Careful ophthalmologic evaluation of patients with ataxia and hypogonadotropic hypogonadism may identify additional cases.