The purpose of this study was to compare bone regeneration in 8-mm defects in 8 New Zealand White rabbit calvaria using 4 different alloplastic bone substitutes. Four 8-mm calvarial defects were made in the parietal bone of each animal. The defects were filled with Bongros-HA™(Bioalpha, Seongnam, Korea), micro macroporous biphasic calcium phosphate(MBCP™, Biomatlante, France), Osteon™(Dentium Co, Seoul, Korea) and Cerasorb (R)(Curasan, Kleinsthei, Germany). Two animals died after surgery. Two rabbits were sacrificed after 4 weeks, and the other 4 were sacrificed after 8 weeks. Data analysis included the qualitative assessment of the calvarial specimens. Histomorphometric analysis was performed to quantify the amount of new bone within the defects. It was found that Osteon™-treated defects had significantly more new bone after 8 weeks thanall other groups. Osteon™ was an effective alloplastic bone substitute which showed reliable osseous healing of critical size defects in the rabbit calvarium. From the results of this study, it is suggested that TCP-coated HA may induce a better bone regeneration ability than either HA or TCP or both.