Most fractures of the shaft of the femur are caused by high-energy trauma. It would be expected that in many cases the ipsilateral knee ligaments are subjected to severe stress. In these days, early diagnosis and proper treatment of combined ligament injury in ipsilateral femoral shaft fracture become to be important and are possible by arthroscope and MRI. We retrospectively reviewed a series of 97 patients with 97 fractures of the femoral shaft from March 1995 to December 1997. demonstrable ipsilateral knee ligament laxity was present in 10(11.3 per cent) of these patients. There were 7 males and 8 left femur fractures. Eight of them were injured by traffic accident. Ten patients were followed for an average months. PCL injuries were five cases and ACL and MCL injuries were two cases each and posterolateral instability was one case. Early diagnosis was possible in MCL and ACL cases but diagnosis was dilayed to average 10 months post-accidentally in PCL injuries. MCL injuries and one ACL injuries were treated conservatively and one ACL and one PCL avulsion fracture were treated with pull-out suture technique and another 4 PCL injuries were treated with reconstruction using bone patella tendon bone, From this study, we advocate careful asessment of the knee, especially PCL injury in all cases of fracture of the femur caused by high-energy trauma.