This report is of a rare case of glioblastoma coexisting with an arteriovenous malformation in a 65-year-old man. Multimodal magnetic resonance imaging (MRI) performed at 3T revealed a necrotic and cystic lesion in the left hemisphere; morphological and metabolic findings were consistent with an infiltrating high-grade glioma, but the presence of dark vessel-like signals on T2* and susceptibility-weighted imaging (SWI) suggested the coexistence of a vascular malformation. The arteriovenous malformation was confirmed by MR angiography and cerebral angiography. The patient was operated on, and histological examination revealed atypical cells characteristic of glioblastoma multiforme and, in the same area, arteriovenous malformation. The possible role of angiogenic factors in this case is also addressed.