Sixteen of thirty-five large-segment allografts that had been implanted after resection for neoplastic conditions, and had been followed for a minimum of thirty-six months, were found to have fractured at a mean of twenty-six months after the implantation. Thirteen of the fractures were treated operatively, and we found a lack of vascularization and soft-tissue attachments to the graft at the fracture site. For seven fractured grafts, there were radiographic and clinical signs of union with the host bone. Eight of the sixteen grafts that had fractured were salvaged with one or more autogenous bone grafts, and two healed spontaneously. Thus, twenty-nine of the thirty-five grafting procedures were considered to have been successful in that the initial objective-provision of a functional segment for skeletal replacement-had been achieved. Multivariate analysis revealed a significant correlation for fracture in patients who were receiving chemotherapy when internal fixation of the graft had included devices that penetrated the cortices of the graft (p < 0.05).