Nerve conduction studies are widely employed in evaluating patients with peripheral nerve disease and are often used serially to measure disease progression or to assess a therapeutic intervention. We determined the inter- and intra-examiner reliability of electrophysiological data by performing serial nerve conduction studies on 7 normal subjects. A high degree of intra-examiner reliability was present, but significant inter-examiner differences were found. Our results suggest that if nerve conduction studies are to be used longitudinally, they should optimally be performed by a single examiner to minimize the degree of variability associated with different examiners.