Juvenile pilocytic astrocytoma of the cerebellum has a benign course and a good prognosis. We report a case of juvenile cerebellar astrocytoma in a 6-year-old girl that underwent surgical resection of the tumor and had two recurrences, 13 and 35 years after first removal. After surgery the patient did not receive any radiation therapy. The last relapse showed histological features of an anaplastic astrocytoma. Six months later the patient died with a diffuse leptomeningeal dissemination. Late malignant transformation of a benign cerebellar astrocytoma is very rare and it is thought to be favored by postsurgical irradiation. The possible pathogenetic mechanisms of this evolution are discussed. This case and the few others reported in the literature emphasize the risk of an unpredictable outcome with the low-grade cerebellar astrocytomas of childhood.