Objective To assess the clinical results of the treatment of the 211 cases of long bone shaft fractures at lower limbs with intramedullary interlocking nails. Methods 211 cases of femoral and tibial fractures were treated chiefly with unreamed intramedullary interlocking nails and postoperative functional exercises including continuous passive motion (CPM). Results 189 cases were followed up for an average of 9 months (ranging from 4 to 26 months). All the cases achieved bone union, and no nonunion occurred. Delayed union occurred in 7 cases and limited knee joint function in 4 cases. According to the Johner-wruhs criteria, 178 cases were assessed as excellent, 24 as good and 9 as fair. The total excellent and good rate was 95.6%. Conclusions The intramedullary interlocking nail is a good device for the treatment of long bone shaft fractures at lower limbs. Its indications have become wider. It is correct to pay equal attention to the blood supply of the fractured bone and the reduction of the fracture during the operation.