This research was designed to study the effect of cryosurgery, phenol cautery, and bone cement packing on the bone tissue. We tried to compare the extent of necrosis by each treatment, and to observe the healing process of necrotized bone. Fifty-two femurs of 26 skeletally mature dogs weighing between 12 and 15 kg were used. A corticocancellous core was removed from the lateral condyle of each femur, and the remaining cavity was treated by the following protocol; no treatment in the control animals, cryosurgery in group 3, phenol cautery in group 2, and bone cement packing in group 4. The animals were sacrificed after 1, 4, and 12 weeks (additionally at 24 weeks in the cryosurgery group). In the cryosurgery group, the extent of necrosis was profound in that the area of necrosis was 36596 in average to compare with the area o#f cavity, and the depth of necrosis extended 2.5-14 mm in average beyond the cavity wall circumferentially. Effect of the phenol was negligable in that only microscopic areas of superficial focal necrosis were found around the cavity wall. Bone cement made an average 153% of area of necrosis, and its depth of necrosis was relatively regular to be between 1.3 and 2.8 mm from the cavity wall. Spots of regeneration in the region of necrosis after the cryosurgery were only scanty until 4 weeks. After 12 weeks, however, definite areas of regeneration were identified in considerable amount, which were almost completely healed after 24 weeks. Regeneration after bone cement packing was rapid to be similar to the control specimens. Clinical Correlation: The cryosurgery could play a significant role as a surgical adjunct to curettage in locally aggressive benign bone tumors as well as in some malignancies. Phenol cautery was not regarded as an adequate treatment after curettage of bone tumors. Though the extent of necrosis was relatively small, bone cement packing was thought to be an useful choice in benign cases.