Object. Diffusion tensor imaging (DTI) has been shown to detect tumor invasion in glioblastoma patients and has been applied in surgical planning. However, the clinical value of the extent of resection based on DTI is unclear. Therefore we retrospectively reviewed the correlation between the extent of resection of DTI abnormalities and patients’ outcome. Methods. We reviewed 31 newly diagnosed supratentorial glioblastoma patients who underwent standard 5-ALA aided surgery with the aim of maximal resection of the enhancing tumour component. All patients received presurgical MR including volumetric T1 post contrast, DTI and FLAIR. Postsurgical anatomical MR images were obtained within 72 hours after resection. The diffusion tensor was split into an isotropic (p) and anisotropic (q) component. The extent of resection was measured for the abnormal area on the p, q, FLAIR and T1 post contrast map. Data were analyzed in relation to patients’ outcome using univariate and multivariate Cox regression models controlling for possible confounding factors including age, MGMT-methylation status and IDH-1 mutation. Results. Complete resection of T1 contrast enhancing tumor was achieved in 24 out of 31 patients (77%). The mean extent of resection of the abnormal p, q and FLAIR area were 57%, 83% and 59%, respectively. Increased resection of the abnormal p and q areas correlated positively with progression free survival (p = 0.009 and p = 0.006, respectively). Additionally, a larger residual q volume predicted significantly shorter time to progression (p = 0.008). More extensive resection of the abnormal q and T1 contrast area improved overall survival (p = 0.041 and p = 0.050, respectively). Conclusion. Longer progression free survival and overall survival were seen in glioblastoma patients in which more DTI abnormality was resected, previously shown to represent infiltrative tumor. This highlights potential usefulness and the importance of an extended resection based on DTI-derived maps.