Extensive bone defects caused by bone tumor resection, osteomyelitis, congenital pseudoarthrosis, post-traumatic bone loss, or femoral head necrosis, require large bone grafts. Such large defects usually are not amenable to conventional, nonvascularized cancellous grafts. By using vascularized bone grafts that do not undergo creeping substitution, that heal rapidly and are not depending on the surrounding tissue, better, safer, and faster results can be obtained. To compare recoveries after vascularized grafts with those after conventional, nonvascularized grafts, experiments were carried out in a rabbit model. They demonstrated good viability and better and faster healing of the microvascular grafts, using radiography, scintigraphy, light microscopy of bone osteocytes and vessels, and tetracycline double-labeling evaluation techniques.