The neurophysiologic monitoring of interventional neuroradiologic procedures is a new field of intraoperative monitoring. Interventional neuroradiology makes use of different diagnostic or therapeutic catheterization techniques in both cerebral and spinal cord arteries. Both procedures can be made more secure by monitoring of EEG or evoked potentials. Using the advantages of the different catheter techniques, such as series of balloon occlusions or injections of drugs or contrast dye, the neuroradiologist and the neurophysiologist are able to plan and test the next steps of an interventional maneuver. The results and implications of neuromonitoring during occluding maneuvers of the internal carotid artery, during local fibrinolytic therapy, during embolization procedures of cerebral or spinal arteries, malformations, or tumors, and during drug application are discussed and illustrated.