The intramedullary nailing is one of the most available methods in treatment of femoral shaft fracture. The closed intramedullary nailing is known to be the best method of treatment of femur shaft fracture, but it is not always available in cases of deficit of equipment, severe associated injury, and some fracture pattern. The open intramedullary nailing has advantage of easily obtaining anatomical reduction but it increases the risk of infection, the incidence of delayed union and additional operations inevitably. We reviewed 33 cases of open intramedullary nailing in femur shaft fracture from September 1994 to September 1997. The results were as follows : 1. The average union time was 27.3 weeks. 2. Location of fractures was middle one-thirds in most cases, and Winquist-Hansen classification type II was the most common. 3. The complication included 8 delayed unions, 3 nonunions, 2 infections, shortening of more than two centimeters in 3 patients. 4. In 4 cases, we did open intramedullary nailing with bone graft initially, but all of them has complication as delayed union and nonunion. We can use open intramedullary nailing method in some femur shaft fractures, but there are many problems and complications. So we must consider it carefully before using this method.