The application of visual evoked potentials (VEP) as a monitoring tool was studied in 40 comatose neurological intensive care patients. With increasing depth of coma, the number of detectable VEP components decreased. In deeply comatose patients, VEP were regularly displayed as a negative wave with a latency of app. 100 ms and an amplitude of app. 8 microV (N100). The administration of promethazine or flunitrazepam used as sedatives produced a decrease of amplitude and an increase of latency of N100 that was reversed within 30 or 60 min respectively. In 10 patients, in which intraventricular pressure (IVP) was measured continuously by means of an intraventricular catheter, it was found that increases of IVP produced a considerable decrease of the amplitude and area of N100; after reduction of the increased IVP, both parameters quickly recovered. These observations indicate that VEP may be a useful tool for neuro-monitoring in neurological intensive care patients.