Recently autogenous nerve graft was usually used for segmental defect of peripheal nerve injury. In case of inappropriate size or amount of donor nerve graft, there were many studies included nerve regeneration with special nerve conduit material. To compare the result of autogenous nerve graft with that of silicone tubing method in segmental defect of sciatic nerve, the experiments were carried out on adult rats with autogenous nerve graft on the left side and silicone tubing on the right side. The results were as follows; 1. Myelinated nerve fibers were larger in silicone tubing method than autogenous nerve graft at postop. 4 weeks. 2. There was no difference in nerve regeneration in both groups at postop. 12 weeks. 3. Some atrophic changes were showed in denervated muscles in both groups at postop. 4 weeks. Skeletal muscle changes between the two groups were meagre. 4. Perineural adhension was rare in silicone tubing group in contrast to autogenous nerve graft group. 5. Nerve Conduction Velocity was similar between autogenous nerve graft and silicone tubing method after 4 weeks postoperatively. In conclusion, this study suggests that silicone tubing can be useful method to repair the large nerve gaps and has a potential clinical utilization in large segmental nerve defect.