Objective：To observe polyethylenimine-mediated BMP-7 gene transfection in promoting fracture healing in elderly rats. Methods：Male SD rats (20-month-old) were randomly divided into 3 groups: group A received BMP-7 gene therapy mediated by polyehtylenimine, group B was treated with normal saline and group C was treated with BMP-7 plasmid without polyethylenimine. Right femoral shaft fracture model was established in all rats. Animals in group A received transdermal injection of pcDNA3.1-BMP-7/PEI; those in group B and C received the same volume of normal saline and pcDNA3.1-BMP-7, respectively. X-ray photography, histological observation (H-E staining), immunohistochemical staining of collagen type Ⅰ, biomechanical and bone mineral density test were employed to assess the healing of fracture 2, 4, and 8 weeks after treatment. Results: The results of X ray and H-E staining showed no fracture healing in the 3 groups during the 8th week after fracture; however, the growth of coloboma in group A was better than that of the other 2 groups, with partial bone union between the fracture ends. Staining of collagen type Ⅰ showed deeper, wider staining in group A compared with the other 2 group. Anti-bending intensity and bone mineral density tests showed that the parameters in group A were better than those of the other 2 groups (P<0.05 or 0.01). Conclusion: Polyethylenimine-mediated hBMP-7 gene transfer can effectively promote fracture healing in elderly rats.