Objective To investigate the clinical results of the treatment of complex femoral and tibial fractures using Grosse Kempf intramedullary interlocking nails. Methods Grosse Kempf intramedullary interlocking nails were used to treat 38 cases of complex femoral and tibial fractures. 12 cases of them were opened fractures, and 26 cases were closed. There were 24 cases of femoral fractures and 14 cases of tibial fractures. The average age was 33.6 years. Most of them were reduced under x ray monitoring. CPM rehabilitation started after the operation to gain the funtional recovey. After two weeks walking with crutches began. Results After the operation, all the wounds healed by first intention. The average union time of the fractures was 10.5 weeks (8～12 weeks). The average follow up period was 14.5 months. With all the cases rated as good or excellent, the clinical results were satisfactory. Conclusion Grosse-Kempf intramedullary interlocking nails are an effective, strong, convenient and secure implant to treat complex femoral and tibial fractures.