Although recent advances in clinical microsurgery have made free tissue transfer a clinical reality, the value of free bone transfers in the reconstructive tumor surgery of long bones was previously reported. Two patients with malignant or aggressive bone tumors who underwent en bloc resection of their tumors and reconstruction with free vascularized bone grafts are presented. In the 1st case, a giant cell tumor of the distal radius was resected and a 10 cm free vascularized fibular graft was performed as a reconstructive procedure; in the 2nd case a chondrosarcoma of the femur was excised and replaced by a 20 cm segment of free vascularized fibula. Postoperatively, these patients were followed with arteriograms and sequential bone scans. The indications for the procedure and the operative technique are discussed. A comparison of the merits of free rib vs. free fibular transfers is presented with emphasis on bony architecture, vessel characteristics, dissection required and the options available for reconstructive surgery. The advantages and disadvantages of free vascularized bone grafts with respect to conventional methods and the potential applicability of this technique are discussed.