Medulloblastoma is classically a childhood tumor, but one third of the cases occurs in adulthood. 17 adult cases are reported here (12 men, 5 women). The average age was 26 years 6 m (from 16 to 47 years). Pre-surgical clinical course is shorter before 30 years (7 months) than after (up to 24 months). Initial symptoms were intracranial hypertension with signs of lateralisation in 2:3 of the cases (cranial nerve and pontocerebellar syndroms). Vertebral angiography, scintigraphy, tomodensitometry helped to the diagnosis. Morphologically, two variants of tumors were found: soft and infiltrative classical medulloblastoma (12 cases) and desmoplastic medulloblastoma which was firmer and better limited (5 cases). The treatment consisted of a surgical removal, as complete as possible, then of an entire neuraxis radiation. Three operated patients died before 6 weeks. Among the 14 other cases, six patients are still alive three years, four other, five years and one, 22 years after the operation. This histological type was of no influence on the post-operative course. Remote metastasis were noted in cauda equina (3 cases), in spinal cord (1 case), in bones and lymphatic nodes (3 cases).