Forty five cases of adult tibial shaft fractures were treated with flexible intramedullary nails under image intensifier at the department of orthopaedic surgery, Capital Armed Forces General Hospital during between April 1986 to July 1988. The results were summarized as follows: 1. 45 cases were all male, the average age was 24.3 years and the most common cause of fractures was sports injury(20 cases) and the second most common cause was traffic accident(18 cases). 2. 11 cases out of 45 cases were open fracture and 34 cases were closed fracture. Eight cases of open fraeture were grade I and three cases were grade II. Twenty eight cases were comminuted fracture. The most common level of the fracture was middle third of the tibial shaft. 3. Average interval from injury to Ender nailing was 13.5 days and the mean duration of permission to full weight bearing was 9.2 weeks. 4. Out of 2 cases of delayed union, the average time of clinical bone union was 9.7 weeks and that of roentgenological bone union was 14 weeks. 5. 11 cases of complication were noted among the 45 cases of tibial shaft fracture which were treated by PGP nailing such as angulation, rotation, ankle joint stiffness, delayed union, shortening, and soft tissue infection. 6. PGP nailing is considered to be a valuable method in treating tibial shaft fracture because of their relative ease of nailing, allowing early weight bearing and decreased complication.