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Twenty-four cases of sporadic olivo-ponto-cerebellar atrophy (OPCA) of adult onset were studied over a period of two years. Results suggest that this disorder has its usual onset in the 5th and 6th decade of life with a male: female ratio of 2:1. It manifests clinically with gait ataxia in all, dysarthria, other cerebellar signs and autonomic involvement in vast majority. There were features of basal ganglia involvement in some. No known identifiable environmental cause was found and genetically they are quite distinct from the known autosomal dominant spinocerebellar ataxias though sporadic occurrence in recessive inheritance or a de novo mutation could not be ruled out completely, but it is unlikely.