We investigated the use of direct lengthening of the distal stump of a peripheral nerve to compare the results of nerve regeneration using the direct lengthening method with simple end-to-end suture and autografting in rats. A segment 10 mm long was resected from the rat sciatic nerve (n=18 in each group). The distal nerve stump was fixed to a ring and pulled at a rate of 1 mm/day for 20 days using an original external nerve distraction device. The results showed that the degree of nerve regeneration in the lengthened group was superior to that of the grafted group electrophysiologically and histologically, but there were no significant differences between the lengthened and end-to-end suture groups. We conclude that direct lengthening of the distal stump of a peripheral nerve can promote nerve regeneration similar to that observed in a Wallerian degenerated nerve. We think that this technique may be used for the treatment of peripheral nerve injuries.