Metastasis from an extracranial tumor to a primary central nervous system tumor is a rare event, and most reported cases concern metastases to meningiomas. The authors describe the first case of leukemic cell dissemination within a glioblastoma. The patient likely presented a genetic predisposition to multiple neoplasms, and the unusual localization of leukemic cells might be partly related to the characteristic microvascular proliferation in glioblastoma.