Background: Physical agents, such as ultrasound, can promote functional restoration and regenerative processes of the peripheral nervous system. However, little is known about the effects of X-ray radiation on nerve regeneration after peripheral nerve injury. The aim of the present study was to investigate the effects of various doses of X-ray radiation on nerve regeneration after sciatic nerve injury in rats. Materials and Methods: The sciatic nerves of Sprague-Dawley rats were transected and repaired via epineurium end-to-end neurorrhaphy. Eighty rats each received single and local X-ray doses of 0 Gy, 0.2 Gy, 1 Gy, 7 Gy and 14 Gy. Functional and morphological assessments of the process of nerve regeneration were performed by using various measurement tools. Results: Compared with the 0 Gy, 0.2 Gy and 14 Gy groups, the 1 Gy and 7 Gy radiation groups experienced significantly increased sciatic functional index, motor nerve conductive velocity (MNCV), expression of S-100, mean diameter of axons, and thickness of myelin sheaths and decreased perineural scar tissue. There were no differences between the 1 Gy group and the 7 Gy group or between the 0 Gy group, the 0.2 Gy group and the 14 Gy group with the exception of MNCV and the expression level of S-100. Conclusion: X-ray radiation in doses of 1 Gy and 7 Gy promoted nerve regeneration after sciatic nerve injury in a rat model. The dose of 14 Gy exerted inhibitory effects, and 0.2 Gy exerted no significant effect on nerve regeneration.