Gabapentin (GBP) is a new, well-tolerated antiepileptic drug found to be effective for painful paroxysmal symptoms (PS) in multiple sclerosis (MS). The aim of this study was to obtain a neurophysiological evaluation of the effects of GBP on the nociceptive system of MS patients suffering PS. We studied 10 MS patients, 6 males, 4 females (mean age 47.3 years), suffering PS (3 had trigeminal neuralgia, 1 painful tonic spasms and 6 dysesthetic or paresthetic symptoms). Three patients were, at the same time, also being treated with carbamazepine. Pain was evaluated by means of the Visual Faces Scale. R3 nociceptive reflex was recorded after 2 weeks' treatment. R3 thresholds and latencies were evaluated and a statistical analysis was performed. A significant variation was found in R3 thresholds between the values recorded before and during GBP treatment; no significant variation was observed in R3 latencies.