Glioblastomas and brain metastases are the most common tumors of the central nervous system in adults. The preoperative distinction between these two entities is important because of their different therapeutic approach and follow-up. Differentiating glioblastoma from brain metastasis is a radiological challenge, particularly in patients with no known neoplastic primary and a solitary brain lesion. Multimodal MRI, using both morphological and functional techniques, is the gold standard for distinguishing these two pathologies. The aim of this work is to illustrate the value of multimodal MRI in differentiating between glioblastoma and brain metastases.For morphological sequences, the most distinctive criteria were: location, number, infiltration of UCS and CC, unenhanced peri-tumoral cortical Flair hypersignal and the ratio of peri-lesional Flair hypersignal to tumor enhancement size.For the perfusion sequence, measurement of intra- and peri-tumoral rCBV in GBM and MC revealed a statistically significant difference between the two tumor types.