Medulloblastoma is an invasive embryonal tumor of the cerebellum with predominant neuronal differentiation. Although several hereditary cancer syndromes have been implicated in medulloblastoma formation, such as Turcot, Gorlin, and Li Fraumeni syndrome, the majority of these tumors cannot be explained by mutations in genes and most medulloblastomas appear sporadically. A 6-year-old girl previously diagnosed with Turner syndrome presented with ataxia and symptoms of raised intracranial pressure. Diagnostic workup disclosed a posterior fossa tumor. Histopathologic study of the excised neoplasm showed a medulloblastoma. The current literature was reviewed; no case of medulloblastoma and Turner syndrome that has been verified on pathologic examination has been reported to date.