Allograft transplantation with concomitant chemotherapy has proven successful in the treatment of malignant bone tumors. However, these chemotherapeutic agents may delay tissue healing, resulting in clinical complications. To clarify the effects of cisplatin on the healing of bone grafts, we studied the incorporation of stably fixed massive diaphyseal femoral syngeneic and allogeneic grafts in rats treated with cisplatin. These data were compared with those of historical controls from animals that did not receive cisplatin. Rats that were to receive a fresh syngeneic graft or frozen allogeneic graft were given cisplatin every 4 weeks starting 9 weeks preoperatively and continuing until the time of death. The total bone area of the graft in animals that received cisplatin was smaller than that of the graft in untreated control rats that did not receive cisplatin. The area of the frozen allograft did not increase between 2 and 4 months. Revascularization was incomplete in cisplatin-treated groups at 2 months, but by 4 months, vessel ingrowth in fresh syngeneic grafts approached control values. Frozen allografts remained poorly revascularized at 4 months. Host-graft union was poor at 2 months in cisplatin-treated rats compared with controls. In cisplatin-treated rats, the host-graft union of the frozen allograft remained inferior at 4 months while that of the syngeneic graft improved. Allogeneic cortical bone grafts are incorporated more slowly and incompletely than syngeneic grafts, and this handicap is exacerbated by the administration of cisplatin.