To fill the large bone defect after bone and soft tissue tumor resection, there are several options such as tumor prosthesis, bone cement with intramedullary nail, autogenous bone graft and allograft. We had used isotrophic autogenous bone graft by using the heat-treated bone removed from tumor site. We analyzed the periods for junctional union and regeneration of autoclaved or low-heat treated groups, and compared these two methods to know which method is better for reconstruction of the bone defect after tumor resection. From Jan. 1987 to Sept. 1993, twelve patients took heat-treated autogenous bone graft: 6 auto- claved, and 6 low heat-treated. Each group had 10 places of junction sites between host and grafted bone. The tumors were 2 cases of osteosarcoma, 3 parosteal osteosarcoma, 2 Ewing's sarcoma, 2 malignant soft tissue tumors, 1 giant cell tumor, and 2 metastases from thyroid cancer and synovial sarcoma. The graft sites were 4 in humerus, 4 pelvis and 4 femur. Two cases showed marginal surgical margin and others wide surgical margin. Here we compare4 the difference between autoclaved group(120℃, 2 atm., 20 min) and low heat-treated group(65℃, 30 min. in water) on the aspect of complications and period to achieve junctional union to host bone. Average follow-up period was 25.3(11 to 88) months. Graft related complications in autoclaved group were bone resorption(2 sites), fracture of grafted bone(2). For low heat-treated group there was no such complication. Nonunion occurred in 3 sites for autoclaved group and 1 for low heat-treated group. Average period for junctional union was 7.3 months(5 to 10 months) for autoclaved group and 6.1 months(5 to 9 months) for low heat-treated group. With these results, heat treated bone autograft may have several advantages such as easy accessi- bility, low cost and anatomical reconstruction of the bone defect. The low heat-treated autogenous bone graft may have more advantages than that of the autoclaved one, and this method may be ratio- nalized to fill the large bone defect made by tumor resection.