Objective:To study the effect on Leptin by investigating the level of Leptin in serum of rats with brain injury and spinal injury combined femoral fracture. Methods:Seventy-two male SD rats were randomly divided into 6 groups:normal control,fracture group,brain injury group,spinal injury group,fracture with brain injury and fracture with spinal injury group(n = 16 per group). Fracture,spinal moderate injury and brain moderate injury models were established. The rats were sacrificed 2,4,8 and 12 weeks respectively after operation,and then the Leptin concentration in serum was detected by rat Leptin. Results:The serum levels of Leptin in the brain injury group,fracture group or fracture with brain injury group significantly increased as compared with that in control group at the 2nd week after operation(P < 0. 05). The concentration of the Leptin in serum of the fracture with brain injury group was higher than other operative group 4 and 8 weeks after operation(P < 0. 05); at the 12th week after operation the difference in above 6 groups was not statistically significant(P > 0. 05). Conclusion:The lever of Leptin in serum was higher in fracture with brain injury group than other groups in certain period,which suggests that Leptin probably makes a comparatively strong responsiveness to fracture with brain injury group.