DSC-MRI was applied intraoperatively during brain tumor removal. Immediately after presumed complete tumor resection an MRI including a dynamic susceptibility contrast T2-weighted EPI sequence was performed in 6 patients while the skull was still open using a flexible two-channel coil system at an intraoperative 1.5-Tesla MR scanner. After an initial baseline period of this iDSC-MRI sequence a bolus of contrast agent was administered intravenously. Maps of relative regional blood flow (rCBF), blood volume (rCBV) and the mean transit time (MTT) were calculated. These maps were compared to preoperatively acquired DSC-MRI data. The extent of the resection was compared with the postoperative MRI performed 24 h after the operation. In five patients complete tumor removal was already achieved at the time of iDSC-MRI and no areas of elevated perfusion values adjacent to the resection cavity were found. Complete removal was again documented on the postoperatively performed MRI. In one case there was residual tumor that showed both contrast enhancement and identical perfusion ratios as in the preoperatively acquired data. Removal of the remaining tumor was performed. iDSC-MRI is technically feasible as there are no significant susceptibility artifacts. DSC-MRI has been used to distinguish different tumor entities preoperatively and recurrent disease from radiation necrosis. Despite brain shift and thus invalidated preoperative image data or contrast leakage caused by intraoperative manipulation, iDCS-MRI furthermore reliably detects residual tumor intraoperatively at a timepoint where further resection is still possible and thus enables the neurosurgeon to complete the resection during the same procedure.