Objective To investigate the treatment of extensive bone defect of distal femur caused by various diseases in adults. Methods From February 1998 to December 2002, 6 cases(aged from 19 to 37) of extensive bone defects of distal femur were treated with two free vascularized fibulae, whose defects were caused by resection ofbone tumor, osteomyelitis and trauma. After the resection of distal femur and articular surface of tibia, the fibulae were transplanted and fixed with screws. And the periosteum of the two fibulae was dissected and sutured with each other.Results The average follow-up time was 3.3 years. Twofree vascularized fibulae could give more support to the body and the bone union of the fibulae was possible when the periosteum was incised and sutured with each other. As time went on, both of the medullary canal reunioned to form a new canal as a whole, which would make the grafts ber. Conclusion Autograft with two free vascularized fibulae can increase the stability in treating extensive bone defect of distal femur, but the union of knee joint will make flexion and extension impossible.