IINTRODUCTION : Reconstruction of large femoral bone defects is a challenge as the aim of such a surgery is not only bone healing but also to reestablish a pain-free, full weight bearing limb. The two main causes leading to a massive femoral defect are malign bone tumors and severe trauma of the lower extremity. Several reconstructive options have been proposed in the literature. The objective of this study is to report our experience in femur reconstruction using a vascularized fibula graft (VFG) in 21 trauma and oncology cases. PATIENTS AND METHODS: We retrospectively analyzed 21 cases of femur reconstruction using VFG between January 1996 and January 2017. 10 patients required reconstruction following bone tumor resection and 11 patients had posttraumatic bone defects. Clinical and radiographic evaluations were performed at regular intervals. Success was defined as full weight-bearing and graft integration. RESULTS : Average patient age was 18 years (range 9-46) in the oncology group and 40 years (range 19-73 years) in the trauma group. Osteosarcoma was the most frequent diagnosis in oncology patients. Bone defects after tumor resection ranged between 12 and 30 cm (mean 20 cm). Consolidation after reconstruction was achieved on average at 9 months (range 3-24 months) postoperatively. The mean follow-up for oncology patients was 97 months (range 36-260 months) Open fractures requiring primary resection of contaminated devascularized bone fragments and bone resection due to posttraumatic osteomyelitis were the main reason for bone loss (mean 11cm, range 6-20cm) in trauma patients. Average time to consolidation was 12 months (range 8-18 months).The mean follow-up for trauma patients was of 79 months (range 20-192 months). The overall success rate was 81% (90% in the oncology group and 72% in the trauma group). The revision rate was 66% (50% in the oncology group and 82% in the trauma group.). CONCLUSION : Successful reconstruction of massive femoral defects with VFG depends on several prognostic factors including, age,the condition of the surrounding soft tissue and the vascularity of the remaining bone at the graft-bone interface. Mechanical stability is a further prerequisite to achieve consolidation. Using a combination of an allograft and a VFG may contribute to greater stability and may thus be advantageous in the reconstruction of massive bone defects.