In certain low-grade malignant bone tumors such as chondrosarcoma or frequent recurrent benign bone tumors as ossifying fibroma, radical treatment may provide a good chance for cure. And large bony defect after the radical treatment can be filled with the massive bone graft. Recent advances in clinical microsurgery have made free vascularized bone graft a clinical reality, and Taylor in 1975, first reported the technique of free vascularized fibula graft for the reconstruction of large tibial defect with excellent clinical results. We tried wide excision and free vascularized fibula graft in 5 patients with ossifying fibroma and one patient with chondrosarcoma from January 1984 to December 1994 and followed for more one year. The shortest bony defect was 7cm and the longest bony defect was 20cm and mean bony defect was 13cm. All patients were evaluated clinically and roentgenographycally on basis of functional recovery and bony union. All patients showed satisfactory functional recovery with sound bony union and showed bony hypertrophy. And, local recurrence was not seen.