Cerebellar astrocytoma in adulthood is a distinct neoplasm with a variable prognosis. We reviewed retrospectively 13 cases in patients aged 21 years or over, seen between 1976 and 1992. These accounted for 19% of all cases of cerebellar astrocytoma seen during that period. The tumour was located in the midline in six patients and laterally in seven; seven patients were females and six were males. The low grade tumours had an overall favourable course, similar to that seen in cerebellar astrocytoma in childhood, with follow-up ranging from 4 to 10 years. The poorly differentiated form, seen in four of the cases, showed progression or recurrence within 4-24 months, regardless of the extent of removal or post-operative radiation therapy.