The purpose of this study was to evaluate the feasibility of using tissue-engineered nerve grafts for delayed repair of peripheral nerve defects. A 1-month delayed, 10-mm long sciatic nerve defect was created for rats, which were divided into three grafted groups and a non-grafted group. For bridging the nerve defects, the rats in three grafted groups were subjected to surgical repair with tissue-engineered nerve grafts made of a chitosan/polyglycolic acid (PGA) conduit filled with neural stem cells (NSCs), chitosan/PGA conduits, and autologous nerve grafts, respectively. At 3 months after nerve grafting, the data from electrophysiology, retrograde tracing and histological investigation revealed that the better outcomes in sciatic nerve regeneration and target muscle re-innervation were achieved in three grafted groups as compared to those in non-grafted group without major differences between three grafted groups. Our results suggest that grafting of chitosan/PGA conduits might be a promising technique for repairing peripheral nerve injuries after a 1-month delay, while introduction of NSCs seem to show no significant additional benefits to regenerative outcomes.