The aim of this study was to analyze the CT and MR features of multiple glioblastomas, and to determine the best imaging modality for the initial diagnosis. The CT (four exams) and MR imaging (eight exams) of eight patients with proven multiple glioblastomas were reviewed by two neuroradiologists. The lesions were always hypo- or isodense on CT and hyperintense on T2-weighted images (100%). They were usually hypo- or isointense on T1-weighted images (90%). Edema and mass effect were very variable. After contrast media administration, the enhancement was mostly strong (71% on CT and 70% on MR), often either heterogeneous or ring-like. The different lesions of a patient often had a different pattern on MR (75% of cases). Meningeal or ventricular enhancement, suggestive of a possible way of dissemination, was rare. In case of multiple cerebral masses, multiple glioblastomas should be considered as a possible diagnosis in addition to the better known diagnosis of brain metastases, abscesses, or multifocal lymphomas. Moderate edema and mass effect on MR associated with strong and heterogeneous enhancement are suggestive of feature of multiple glioblastomas. Magnetic resonance allows rarely the visualization of a dissemination route.