SUMMARYThe somatosensory evoked response amplitured and latency recovery functions have been determined in 11 normal subjects and 10 patients with MS. The results show [1] no difference in the amplitude recovery between the groups and [2] a significant shortening of the patient test stimulus latency at shorter interstimulus times. These results suggest that: Diseased or demyelinated axons cannot effectively respond to a test stimulus that follows a conditioning stimulus by short intervals (less than 60 msec). The more heavily myelinated and fastest conducting fibers are selectively more affected by the demyelination process. The application of this method holds promise for assessing neuronal conduction in MS patients in comparison to normal subjects.