Infected nonunion of the long bone, while less common today than in the past, continues to challenge orthopaedic surgeons. Various treatment methods including current techniques of internal fixation, bone graft, electrical stimulation and external fixation have been tried, but results are not always satisfactory. Authors reported successful treatment of infected nonunion by rigid internal fixation with one plate and autogenous bone graft in previous volumes 1989. Recently we adopted dual plate method, by which we overcame a greater amount of bone defect and obtained more rigid internal fixation. We have treated 14 cases of infected nonunion with this method from Oct. 1992 to Oct. 1994, and the results are as follows; 1. Tibia fractures were 9 cases, and femur fractures were 5 cases. 2. Six cases showed large bone defect. The average bone defect was 4.5cm in length and we could overcome it by Dual plate method and autogenous bone graft. 3. Six cases which showed large bone defect were united in average 5 months. 4. In remaining 8 cases, union was obtained in average 3 months.