The rigid internal fixation of femur and tibia shaft fracture with intramedulary nailing enables early joint motion and weight bearing. This proecdure has been used with wide popularity because it is possible simultaneously to preserve the range of motion and to obtain the bone union. But in the proximal and distal femur and tibia fracutre, sine the interloking screws are too close to the fracture, the rigid fixation cannot be achieved and when early weight bearing is done, failure of the metal is possible. These problems have raised opposition to the use of intramedullary nailing. Ten cases of fracture of proximal or distal femur and tibia closed to joint line and 25 cases of femur and tibia midshaft fractures treated with interlocking intramedullary nailing were reviewed from August 1st., 1989 to May 31st., 1990 with follow up more than 1 year and these cases are presented with review of references. The results were as follws; 1. In distal one-third fracture of femur (2 cases) and tibia (4 cases), by using nail adjusted length for each fractures, rigid fixations were achieved. 2. In subtrochanteric (2 cases) or midshaft fractures of femur with femur neck fractures (2 cases), stability of both fractures was obtained by using reconstruction nail and early ambulation was possible and all cases had bone union. 3. In delayed and non union of tibia (3 cases), and non union of femur (1 case), interlocking nailing was applied. Union was achieved in all 4 cases without bone graft or cast immobilization. 4. Among 25 cases of midshaft fracture, union was obtained in 22 cases (92%) at 3rd month, delayed uniuon occured in three cases but union was achived after dynamization (2 cases) and bone graft (1 case) at 6th month.