Neuromuscular function was evaluated in long-term type I diabetic patients who retained a functioning pancreas graft. A group of 34 patients was examined at 1 year and another group of 11 patients at 2 years after pancreas transplantation. In this report the clinical and electrophysiological course of motor features of poly-neuropathy are described. Before pancreas transplantation, clinical evidence of polyneuropathy was present in all patients. The mean motor nerve conduction velocities (NCV) were below normal and the mean amplitude of the evoked muscle action potentials (MAP) were in the low normal range. The observed abnormalities of muscle strength and tendon reflexes had not progressed in these intervals. Motor NCV improved slightly and MAP amplitude was essentially unchanged. These preliminary results indicate that the progression of diabetic polyneuropathy may be halted by successful pancreas transplantation.