The present study evaluated of regeneration effect of platelet rich plasma on the treatment of grade II furcation involvement, with coralline calcium phosphate bone in humans. 30 teeth with grade II furcation defect were selected and 15 teeth(control) were treated with coralline calcium phosphate bone, the others(test) were treated with coralline calcium phosphate bone and platelet rich plasma. Pocket depth, clinical attachment level, width of keratinized gingiva width were measured at baseline, postoperative 3, 6months. from cementoenamel junction to alveolar crest and fundus were measured at baseline, 6months(re-entry). Both groups were statistically analyzed by Wilcoxon signed Ranks Test & Mann-whitney Test using SPSS program(5% significance level). The results were as follows: 1. Pocket depth, clinical attachment level, keratinized gingva width, cementoenamel junction - alveolar crest, cementoenamel junction - fundus were not differ significantly in both groups at baseline 2. The change of pocket depth, clinical attachment level, keratinized gingva width, cementoenamel junction - alveolar crest, cementoenamel junction - fundus in both groups were decreased significantly at 3, 6months(p<0.05). 3. The change of pocket depth, clinical attachment level in test group decreased significantly than control at 3, 6months(p<0.05). 4. The change of keratinized gingiva width, cementoenamel junctional - alveolar crest, cementoenamel junction - fundus were not differ significantly in both groups at 3, 6months. 5. The pocket depth, clinical attachment level, keratinized gingiva width exhibited marked changes at 3 months in both groups. In conclusion, the results of this study suggest that platelet rich plasma have adjunctive clinical treatment effect to periodontal regeneration in grade II furcation defects.