Infected large defect of the long bone have had many obstacles in treatment. It is usually very difficult to obtain union and to correct coexisting infection, deformity, & leg length discrepancy, Allograft transplantation have been traditionally used to treat infected large defect of the long bone. And Ilizarov technique has recently gained popularity as a multifactorial approach to the management of infected large defect of the long bone. We performed allograft transplantation in 5 cases and Ilizarov technique in 6 cases with infected large defect of the long bone at National Medical Center from 1987 through 1991. The results were as follows; 1. In the cases of allograft transplantaton, the average size of the bone defect was 9.6cm (range from 6cm to 3cm) and the average length of leg length discrepancy was 2.4cm (range from 0cm to 4cm). 2. In the six cases of Ilizarov technique, the average size of the bone defect was 2.5cm(range from 0.5cm to 4.5cm) and the average length of leg length discrepancy was 3.7cm(range from 0cm to 7cm). 3. In the cases of allograft transplantation, the bone union was achieved in two cases. Two cases have been followed up for 19 and 26 months each and they showed complete bone union in the proximal side of host-graft junction, but not complete union in the distal side. In one case, developed the osteolysis of the grafted bone due to the infection. After operation, the average length of leg length discrepancy was 1.4cm(range from 0 cm to 2cm). 4. In the cases of Ilizarov technique, bone union was achieved in three cases. One case have been followed up for 15 menths and showed incomplete bone union. In two cases, additional operation was performed due to the nonunion and the fracture between the junction of the proximal bone fragment and the transportated bone fragment in each. So we report our results of diferent two methods of treatment even if limited cases and experiences.