Cortical allografts and free vascularized fibular grafts are the most commonly used techniques for the reconstruction of large bony defects following tumor resection. Unfortunately, large bony allografts have a high complication rate. The three most common complications following large allograft transplantation are infection, nonunion and fracture, all related to the bones avascular status. Free fibular grafts provide vascularized bone, but often lack the structural strength of large allografts. In addition, adequate fixation is difficult as plate and screw fixation can compromise periosteal blood flow. To overcome these disadvantages, a new method of combining a structural allograft with an intramedullary free vascularized fibular graft was developed. Here we report our initial findings with this technique. Methods: Six patients who had large bony defects following tumor resection were reconstructed with an allograft-vascular fibular construct. Initially, cortical allograft was fashioned to fit the resection defect. The allograft was then reamed so that the medullary segment would accept the fibular graft. The free fibular graft was then passed through the intramedullary canal and doweled into the proximal and distal ends of the patients remaining bone. The fibular vessels were brought out through a window in the allograft to allow for anastomosis. Fixation was then applied to the allograft. Grafts were evaluated for viability with post-operative bone scans. Time to union was evaluated radiographically. Patients’ charts were evaluated for post-operative complications. Results: There were 2 female and 4 male patients. The average age was 11.5 years. Three cases involved femoral reconstruction and three involved tibial reconstruction. One case involved replacement of a failed allograft used for femoral reconstruction. 3 patients underwent chemotherapy during the post-operative course. Average allograft length was 14.5 cm, while average fibular length was 20.2 cm. The average follow-up time was 26 months. Bony union of the fibula to the allograft and native bone averaged 8 months. Free fibular grafts became incorporated into the allograft. There were no stress fractures or infections. Two cases required additional bone grafting to obtain union between the allograft and native bone. One patient developed a non-union at the donor leg syndesmosis site. Limb salvage was 100%. All patients returned to independent ambulation. Conclusion: This new technique provides the reconstructive benefits of vascularized bone with the cortical rigidity of an allograft for large bony defect. The free fibular graft provides vascular ingrowth to the allograft, which accelerates bony healing. The technique allowed for excellent functional limb salvage.