Curettage without bone graft was performed in 17 patients with benign bone tumors and tumor-like lesions. New bone formation with uniformly increased radiodensity appeared in serial plain radiographs within 3 months after the operation. The average period before full weight could be borne on the lower extremities was 14 weeks. Computed tomography revealed that the central part of the bone lesions persisted without bone formation. The thickening of cortical bone was predominant. These data indicate that enough mechanical strength for daily activity will be recovered by bone within 4 months after curettage without any filler, although remodeling continues for over a year. It is suggested that bone graft and implantation of "biomaterials" are not necessary in patients, especially younger ones, with benign bone tumors or tumorous conditions.