Familia1 essential tremor (ET) is an autosomal dominant disorder presenting as an isolated postural tremor. Its frequent association with dystonia suggests that the two disorders might be pathogenically related. We report the exclusion of the DYTl locus on chromosome 9q32–34, responsible for idiopathic torsion dystonia (ITD), in two large ET families. We conclude that ET and ITD are distinct genetic disorders.