The use of lyophilised bone from calves as a heterograft was introduced by Maatz and Bauermeister in 1957 as an alternative to autografts and freeze-dried homografts which were then in general use. The Kiel bone was known to possess no antigenecity and serial radiographs revealed that it is incorporated into the recipient site by a process of creeping substitution from surrounding bone. In patients with benign bone tumors, the surgical dead space was filled with Kiel bone graft in the departments of orthopedic surgery, Pusan national university hospital. The results were followed up for more than 14 months, and were evaluated by the palin film findings. The results were as follows : l. Of the 22 cases, satisfactory result was obtained in 18 cases(81,8%). 2. The mean lesion size(diameter of lesion/diameter of bone)of success cases was 61.6%, and the mean lesion size of failed cases was 82.8%. 3. The duration from the Kiel bone graft to the evidence of new bone formation and remodelling was 10.5 months on an average with a range of 7months to 15months, and the duratin from the Kiel bone graft to the complete resorption of the Kiel bone was 45.7 months on an average with a range of 29 months to 66 months. 4. The causes of the failed cases were thought to be incomplete removal of the lesion, decreased vascularity due to repeated surgery, large size of the lesion, and the potentiality of tumor, 5. It was difficult to evaluate success rate according to underlying disease because the number of the cases was not large enough, but giant cell tumor showed high recurrence rate.