Electrophysiological and clinical assessment of recovery of function was undertaken on 34 median and 33 ulnar nerve which had been resutured after complete section three and a half months to 24 years previously. An evaluation of different methods of repair was attempted. Our results suggested that re-exploration of the site of suture is indicated in the absence of voluntary activity on needle EMG by seven months (12 months for grafts), of an electrically evoked muscle action potential, measurable distal motor latency, or motor nerve conduction velocity by 10 months (14 months for grafts), or of clinically detectable voluntary muscle movement by 10 months after suture. By present techniques of repair useful prognostic information cannot be obtained by a consideration of sensory parameters either clinical or electrophysiological.