An investigation on the fate of bone grafts in 38 patients, who had been subjected to a partial resection of the mandible for benign and malignant tumours, is presented. Apart from thorough drainage, meticulous suturing and gastric tube feeding, high and prolonged administration of antibiotics was practised to prevent infection. The basic antibiotic coverage in most patients consisted of 4 X 3 grams of flucloxacilline intravenously during ten days. After this period revascularization of a bone graft may be assumed to have progressed to such a degree, that thereafter the graft can "defend itself" against invading micro-organisms, if necessary supported by further lower dosage antibiotic treatment. In 28 patients no complications were encountered. Ten patients showed signs of infection, leading to complete loss of the graft in 3 patients. Incision, drainage, removal of sequestra and further antibiotic treatment resulted in preservation of the major part of the grafts in the other 7 patients. No correlation of infection with type of fixation, extent of soft tissue resection or time at which the reconstruction was done (primary or secondary) was found. The basic difference of maxillo-facial bone grafting as compared to bone grafting in other areas of the body is stressed, massive primary contamination combined with dead space and maybe dehiscence of the oral wound margins being mainly responsible for the relatively unfavourable conditions for grafting in this region.