Normal control somatosensory evoked potential data (elicited by stimulation of the posterior tibial nerve), of 20 healthy subjects were compared to the electrophysiological data of 20 patients with the diagnosis of definite or probable multiple sclerosis. The demyelinating process affects all segments of the response, causing increase in latency and decrease in amplitudes as well as lack of the potentials during the disease. Based on the literature, the neurological localization values of TPSEP are summarized. Due to its outstanding sensitivity in these cases, the procedure as advised by the authors should be used in demyelinating processes and in other spinal cord disease of different aetiology.