The search for useful bone graft substitutes historically has focused on biologic alternatives. TCP has a 36% porosity and variable pores ranging from 100 to 300µm in diameter. They are biocompatible, easy fabricated into any size or shape, and offer a chemical environment and surface conductive to new bone formation. The porous scaffolding of the TCP permits rapid bone ingrowth. Gradual replacement of the ceramic with mature remodelling bone is noted as bioresorption of the TCP proceeds. The author investigated with TCP to evaluate the effect on the healing process of canine femoral bone defect as a bone graft substitutes. Five mongrel dogs(12Kg) were used in this study. Two holes(3.5mm) were created artificially with drill on the lateral surface of both right and left distal femora metaphyseal area in each dog under general anesthesia with nembutal. After creating artificial bone defects, 1 bone defect hole was filled with biodegradable TCP ceramic and adjacent other one was used as a control site wthout filling any implant material. The interval of each observation was 4, 6, 8, 10, 12 weeks after implantation and examined by means of radiology, histology with light and electron microscope. The results obtained were as follows; 1. Lamellar bone was formed around TCP 8 weeks after implantation. 2. In peripheral areas of TCP, collagen fibers, cytoplasm of osteoclasts & osteoblasts present in micropores of TCP. Osteocytes appeared around TCP with time. 3. In central areas of TCP, amorphous matrix was deposited in micropores in the early phase(4 weeks), but later collagen fibers & cytoplasmic processes appeared. 4. Osteoclasts were collected around TCP granules. Size of TCP granules in the periphery was gradually decreased. 5. Foreign body reaction within tissue was not shown during a whole experimental period. 6. Radiologically, opacity of implanted TCP was gradually decreased, and spillage on soft tissue of TCP was resorbed rapidly.