The endosseous dental implants of glass-ceramic were implanted and holes were drilled as control in edentulous areas of adult dog mandibles. The implants were kept without function. After 2-84 days, the biological reaction of the tissue was examined by histological and ultrastructural methods, while the glass-ceramic surface was examined by EPMA analysis and X-ray diffraction. The results were as follows: 1. After 4 days the bone matrix formation started on the surface of the glass-ceramic. After 14 days, the area of bone formation on the implant surface was enlarged and about all surface was covered with this woven bone. 2. Being compared with the control, glass-ceramic didn't prevent the healing process of bone. 3. On the surface of glass-ceramic, apatite and beta-whitlockite crystal formation was observed by X-ray diffraction. And analysis by EPMA showed this areas combined bone. 4. TEM observation showed that there were many hemidesmosomes in interface between the implant and attached epithelium. In the subepithelial fibrous tissue collagen fibers and fibroblasts were arranged in parallel on the implant surface.