Objective: To study the protective effect of grafting NT-4 genetically modified cells on injury of spine motoneurons in rats. Methods: NT-4 genetically modified cells were obtained by infecting L-6TG cell in vitro with a retroviral vector pN2A containing the rat NT-4 cDNA gene. The rats with left sciatic nerve apocoped were taken as model for treatment by implanting NT-4 genetically modified cells. The right sciatic nerve was taken as control. The Nissl staining and ChE staining in motoneurons of spine were also studied. Results: There were significant differences between groups of NT-4 and control in the Nissl staining and ChE staining. Conclusion: Grafting NT-4 cells can prevent most motoneurons from death.