Forty-seven patients with Glioblastoma (42) and Anaplastic Astrocytoma (5) were studied with MR 24 hrs after surgery. In order to evaluate the role of early MR in defining the extent of surgical resection and its relation with the prognosis of malignant glioma patients, three categories of surgical resection were considered: gross total, sub-total and partial resection. The results were correlated with progression-free survival (PFS) and overall survival (ST). As demonstrated by early-MR, gross total resection was performed in 17 patients, sub-total and partial resection in 19 and 11 patients, respectively. The PFS was 6 months in gross total resection, 6 and 3 months in sub-total and in partial resection, respectively. The median survival time was 16 months in total resection patients, 13 months and 7 months in sub-total resection and partial resection patients, respectively. The study confirms that early-MR has to be considered an accurate technique for monitoring the extension of malignant glioma surgical resection and shows a good correlation between early-MR findings, PFS and ST.