Proximal shaft fractures of the tibia have a high incidence of complication and often result in poor outcomes. Plate fixation and locked intramedullary nailing are the most common methods of treatment, but now the latter is more popular because of soft tissue problem, osteomyelitis etc.. The purpose of this study is to evaluate the results of locked intramedullary nailing in the treatment of proximal shaft fractures of the tibia and to draw a conclusion that what type of fracture patterns are the appropriate indication of nailing. We analyzed 18 proximal shaft fractures of the tibia which were treated by locked intramedullary nailing from October 1991 to March 1997 and followed more than 12 months. The results were as follows ; The complications were occurred in 12 cases(66.6%); 4 cases of delayed or non-union, 8 of angular deformity, 1 of leg length discrepancy. Delayed or non-unions were caused by fracture site comminution and bone defect. 5 anterior angular deformities were due to the pulling of the knee extensor mechanism and 3 valgus deformities were due to medially located entry portal. In conclusion, since locked intramedullary nailing in proximal tibial fractures causes a high incidence of complications, it is recommended in transverse or undisplaced fractures. And plate fixation and bone graft will be recommended in comminuted or displaced oblique fractures, if soft tissue condition is permitted.