The ultimate goal of periodontal therapy is to promote the regeneration of lost periodontal tissue, there have been many attempts to develop a method to achieve this goal, but none of them was completely successful. The purpose of this study is to evaluate the effects of Bio-Oss(R) on alkaline Phosphatase (ALP) activity in human fetal osteoblasts (hFOB1). The results of this study were as follows, in ALP Activity, 100 microgram/ml Bio-Oss(R) treated group showed significantly increased value than negative control group, but positive group(10(-7) M dexamethasone treated group) showed the highest ALP activity at 3 day. In mineralization assay, numerous mineralized nodules were identified as darkly stained spots in 100 microgram/ml Bio-Oss(R) treated group than two control groups, whereas a small number of mineralized nodules were showed in the positive control. ALP may relate to the initial phase of bone nodule formation. On the basis of these results, this study showed Bio-Oss(R) is capable of accelerating new bone formation through hFOB1 differentiation in vitro.