The clinical and pathological findings in a boy suffering from Machado-Joseph disease are described. The patient was the son of two affected parents and signs first appeared at the age of 8 years. A younger brother also became affected at the age of 7. The patient presented all the characteristic features of the disease which consist of progressive cerebellar ataxia, pyramidal signs, progressive external ophthalmoplegia with variable degrees of extrapyramidal and peripheral signs. He died at the age of 15, after an unusually short duration of the disease. Pathological examination showed degeneration and mild gliosis of the substantia nigra, dentate, pontine and cranial nerve nuclei, anterior horns and Clarke's columns. Additional findings, not previously described were the involvement of sensory ganglia, intermediolateral columns and gracile and cuneate nuclei. It is suggested that the present case is homozygous for the gene of Machado-Joseph disease. The pattern of distribution of the pathological lesions and the sparing of some anatomical structures confirm our view that Machado-Joseph disease should be considered a distinct clinico-pathological entity within the group of the autosomal dominant ataxias.