We report upon a Dutch autosomal dominant cerebellar ataxia (ADCA) family, clinically characterized by a late-onset (>40 years), slowly progressive, isolated spinocerebellar ataxia (SCA). Neuropathological examination in one affected subject showed neuronal loss in the Purkinje cell layer, dentate nuclei and inferior olives, thinning of cerebellopontine tracts, demyelination of posterior and lateral columns in the spinal cord, as well as ubiquitin-positive intranuclear inclusions in nigral neurons that were considered to be Marinesco bodies. Data obtained from the genome-wide linkage analysis revealed a maximal lod score of 3.46 at = 0.00 for marker D20S199. This new SCA locus, on chromosome region 20p13-p12.3, was designated SCA23 after approval by the HUGO Nomenclature Committee. Currently, candidate genes are being screened for mutations within the SCA23 interval. In addition to the recently identified SCA14, SCA19 and FGF14 families, SCA23 is yet another novel SCA locus in the Dutch ADCA population, which further defines the genetic heterogeneity of ADCA families in the Netherlands.