Background: Clinical descriptions of the dominantly inherited ataxic motor syndromes in a 7-generation family of German origin were first reported in 1951. Objective: To provide follow-up clinical, pathological, and genetic data for 9 patients in this family. Design: Clinical histories and neurologic findings, gross and microscopic pathological features, and DNA analysis. Results: Clinical presentations in this closely followed up portion of the family include fairly uniform ataxic and upper motor neuron symptoms. Nystagmus was a conspicuous and early sign, but generational anticipation was not evident. Although often present, amyotrophy was not a major source of disability. Major pathological degeneration was noted in the pons, spinal cord, and upper brainstem, where ubiquitin-immunoreactive intranuclear inclusion bodies were demonstrated. The diagnosis of Machado-Joseph disease (SCA3 [spinocerebellar ataxia type 3] genotype) was established from autopsy tissue in 1 patient and from blood specimens in 6 others. Conclusions: Clinical variation within this family and between this family and families with the SCA1 and SCA3 genotypes is so broad as to make the genetic diagnosis from clinical criteria alone practically impossible. The pathological definition of Machado-Joseph disease is more reliable, but some findings do overlap those of other genotypes. To our knowledge, the basis for the phenotypic variations in Machado-Joseph disease, genetic or otherwise, has not been established.