It has been known that periods of absorption varies allografts or xenografts of transplantations of freeze-dried cortical bone(FDCB). In this study changes of absorption of FDCB in xenograft transplantations were evaluated according to extracted time with chloroform-methanol solution(CM sol.). The FDCB from pig was removed soft tissue by surgical knife. Fat of the FDCB was removed with treatments of CM sol. for 2, 6, and 10 days, then the treated FDCB was freeze-dried at $-80^{circ}C$ and sterilized with ethylene oxide gas. The FDCB was transplanted to fifteen millimeter artificial-defected regions of 6 dogs on fibular diaphyses. This was biweekly examined by radiograph for 18 weeks. In result new bone formation with FDCB treated for 6 days was higher than the other bones treated for 2 and 10 days. Duration of absorption with FDCB treated for 6 days was longer than the others. The remain with FDCB treated for 10 days was more than the others.