Heat-treated autogenous bone graft has been utilized in the cases with large hone defects associated with tumors, chronic osteomyelitis, and trauma. Conventional autoclaved autogenous bone grafting, however, has inherent disadvantages that included decreased biomechanical strength, and loss of osteogenesity. In contrast, despite devitalizing the tumor cells, low heat-treatment can render autogenous hone grafts to retain better biomechanical strength as well as to preserve osteogenesity by avoiding destruction of hone morphogenetic protein. To investigate biomechanical strength and osteogenesity of heat-treated autogenous bone grafts, rahbits were classified into three groups: groupl, in-situ implantation of autogenous graft in the diaphyseal defect of the tibia without any heat treatment; group 2, reimplantation of graft after low heattreatment; group 3, reimplantation of graft after autoclaving. Radiological, histological, and scintigraphic examination were performed postoperativeIy at 2nd, 4th, 6th, 9th, 12th weeks. And biomechanical test was performed postoperatively at 6th, 9th, 12th weeks. Biomechanical test revealed that there were no statistical differences among three groups at 6th week and 9th week. However, at 12th week postoperatively, there were significant differences between group 2 and group 3, and between group 1 and group 3. Radiological and histological examinations showed that new bone formation started earlier in groups l and 2, compared to group 3. Also bone remodeling was advanced in group I and 2, com- pored to group 3. Scintigraphically, the increase of 99mTc-MDP uptake was delayed in group3, compared to group l and 2. Based upon above findings, it was concluded that low heat-treated autogenous bone grafting was hetter than autoclaved autogenous bone grafting in promoting bone healing with retained biomechanical strength.