Reconstruction after excision of the femur and tibia malignancy is a challenging issue for the reconstructive surgeon. The combined use of a vascularized fibular flap and allograft can provide a reliable reconstructive option. This article describes the authors' experience with this technique for the treatment of large-segmental bone defects after intercalary resection of lower extremity malignancy. From 2003 to 2008, 11 patients that had intercalary resection of lower extremity malignancy underwent reconstruction with an allograft and vascularized fibular construct. Time to union was recorded through evaluation of plain radiographs. Patients were examined clinically and radiographically and were assessed functionally with MSTS score. The average age at time of operation was 18.5 years. The mean follow-up time was 34.1 months. The oncology result was continuous disease free in 7 patients, no evidence of disease in 2, alive with disease in 1, and died of disease in 1. Free vascularized fibula flap was used in 7 patients and ispilateral pedicle vascularized fibula in 4. The average length of the resected segment was 12.1 cm and that of the fibula flap was 16.2 cm. The primary unions were achieved in all patients except one with tibia reconstruction. The average time for bone union was 5.4 months at fibula-host junction and 11.8 months at allograft-host junction. There were no allograft fractures and no infections. Five patients had 7 local complications. The MSTS average score was 91.8% at final follow-up. The mean time of weight-bearing was 12.4 months. Intramedullary fibular flap in combination with massive allografts provide an excellent option for reconstruction of large-bony defects after lower extremity malignancy extirpation. The viability of the fibula is a cornerstone in success of reconstruction that prevents allograft nonunion and result in decreased time to bone healing, leading to earlier patient recovery and return of function.