Loss of teeth causes the inevitable reduction of residual ridge. Among the various methods solving this problem, hydroxyapatite proved to be useful for correction of ridge defect and irregularity. The purpose of this study is to evaluate the tissue responses of two types Of hydroxyapatites and resin polymer. Calcitite 2040 (Calcitek Inc.), Interpore 200 (Interpore Int.), and HTR polymer (HTR Sciences) were implanted into the jaw of an adult dog. The procedure was designed to obtain the results of 1 week, 2 week, 4 week, and 12 week-intervals. And after 12 weeks from the first operation day, the dog was sacrificed and evaluated histologically by light microscope. The results were as follows : 1. The mucosa was healed after two weeks. 2. After 1 week, there were acute inflammatory cells, but diminished after 2 weeks and were not seen after 12 weeks. 3. The hydroxyapatites implanted in soft tissues were surrounded by fibrous connective tissue. And some foreign body giant cells were found. 4. Calcitite and Interpore particles implanted subperiosteally were surrounded by newly formed bone after 12 months. And direct contact between bone and particles was noted. 5. The HTR particles implanted in soft tissues were encapsulated by fibrous connective tissues. The sample where the particles contacted directly to bone could not obtained by some probable insufficiencies of surgical technique or care of the animal. And the residue of HTR particles was digested by macrophage.