Herein we describe the molecular and clinical findings in a North American Caucasian family with dentatorubral-pallidoluysian atrophy (DRPLA). These patients all presented with an autosomal dominant neurodegenerative disorder characterized by a variable combination of clinical symptoms including seizures, ataxia, dementia, choreiform movements, mental retardation, and psychiatric disease. Neuroradiologic findings in the index case revealed deep subcortical white matter changes on magnetic resonance imaging. Prior to referral, the family carried a diagnosis of Huntington's disease (HD). Subsequent direct molecular testing for HD failed to identify the HD expansion mutation in affected individuals. Molecular testing for DRPLA, however, demonstrated the presence of the recently characterized DRPLA expansion mutation in all affected individuals. The size of the expansion correlated with the age of onset of clinical symptoms. As DRPLA has rarely been reported in North American and European populations, the molecular confirmation of DRPLA in this family provides support for the hypothesis that DRPLA may not be as geographically restricted as once thought.