PURPOSE: To analyze the result of free vascularized fibular grafting for treatment of infected nonunion of the tibia with radical bone and soft tissue defect. MATERIALS AND METHODS: 17 patients with infected nonunion of the tibia who underwent a reconstruction using free vascularized fibular grafting were reviewed retrospectively. The mean follow-up period was 70.3 months. We analyzed the results radiographically which included the time of bone union, the amount of hypertrophy of grafted bone and complications. RESULTS: The average length of bone defect was 8.8 cm (5~15 cm), and the average length of fibular graft was 14.1 cm (10~17.5 cm). Bony union was achieved in 11 of 17 cases and the average time of bone union was 5.2 months (4~6 months). There were 6 cases of nonunion. All nonunions developed at the proximal end of graft in patients who underwent fixation using pin and external fixator. Union was eventually achieved in all cases in 6.0 months (5~8 months) after the cancellous bone graft and plate internal fixation. Hypertrophy of grafted bones with more than 20% developed only in 4 cases out of 17. There were 3 cases of stress fracture, however there was no recurrence of infection or serious donor site morbidity. CONCLUSION: Free vascularized fibula grafting is one of the most effective reconstruction options for the infected nonunion of the tibia with radical bone and soft tissue defect. Strong internal fixation using plate and screws is required to reduce the rate of nonunion and stress fracture of grafted fibulas.