Two families with autosomal dominant spinocerebellar ataxia (SCA) of late onset were studied. These families originate in the same small rural area in a Southern Italian region (Calabria). We report the clinical study of 23 patients in different stages of the disease and neuropathological study in one patient. Linkage studies provided strong evidence for linkage of the SCA locus to the HLA loci (SCA1) in the subjects of these families. Our study allows to outline the clinical features of HLA linked SCA in order to trace a pattern of SCA1 phenotype thus making easier the identification of SCA1 heterozygotes in an early clinical stage.