We describe the unusual case of a 51-year-old woman with spinocerebellar ataxia type 1 (SCA1) who showed choreiform movements in addition to cerebellar ataxia. To date, extrapyramidal signs including involuntary movements have been rarely reported in SCA1. Surface electromyogram in our patient revealed grouped discharges whose duration was longer than that of chorea observed in HD, indicating that the involuntary movements represented choreoathetosis rather than pure chorea. These choreiform movements have not been seen in non-hereditary spinocerebellar ataxia. Therefore, if "sporadic" cases of cerebellar ataxia show such movements, the possibility of genetic origin of the ataxia is high and a surveillance of various forms of hereditary spinocerebellar ataxia including SCA1 is required.