Malignant astroglial neoplasms of the cerebellum are rare and the clinical behavior of these tumors is unpredictable. The authors describe the histological characteristics and clinical outcome in 10 patients; eight had malignant cerebellar astrocytomas, and one each had an astroblastoma and a true polar spongioblastoma. Malignant glial tumors involving the cerebellum usually behave very aggressively. Cerebellar astroblastomas and polar spongioblastomas are too rare to predict their natural history. Some hypotheses are proposed concerning the evolution and interrelationship of malignant glial tumors of the cerebellum.