The ultimate goal of periodontal therapy is the regeneration of periodontal tissue and repair of function. For more than a decade there have been many efforts to develop materials and bioactive molecule(such as growth factor and differentiation factors) to promote periodontal wound healing. Among the bioactive molecules, bone morphogenetic protein(BMP) was studied for periodontal wound healing. Since Urist demonstrated that demineralized bone matrix could induce the formation of cartilage and bone in ectopic site, many studies on BMP have been reported. Among those BMPs, it was reported that rhBMP-2 enhanced the healing of bone defects in animal studies and clinical studies. However, its efficacy in periodontal regeneration, especially 1-wall intrabony defects is still unknown. The purpose of this study was to examine the effect of rhBMP-2/ACS on the epithelial migration, gingival connective tissue adhesion, cementum formation, alveolar bone regeneration in intrabony defects of dogs. Four millimeter deep and four millimeter wide 1-wall defects were surgically created in the mesial aspects of the 3rd incisors. The test group received rhBMP-2/ACS with a flap procedure and the control underwent buffer/ACS with a flap procedure. Histologic analysis after 8 weeks of healing revealed the following results: 1. The length of epithelial growth(the distance from alveolar crest to the apical end of JE) was 0.9+/-1.5mm in the control group and 1.2+/-1.4mm in the test group. There was no statistically significant difference between the two groups. 2. The length of connective tissue adhesion was 2.4+/-1.3mm in the control group and 1.2+/-1.1mm in the test group. The control group showed significantly enhanced adhesion(P<0.05). 3. The length of new cementum was 0.9+/-1.0mm in the control group and 1.7+/-0.8mm in the test group. The test group showed significantly enhanced cementum regeneration(P<0.05). 4. The length of new bone height was 1.9+/-0.6mm in the control group and 2.4+/-0.9mm in the test group. There was no statistically significant difference between the two groups. 5. The new bone area was 4.7+/-1.7mm2 in the control group and 8.0+/- 2.0mm2 in the test group. The test group showed significantly enhanced bone formed area(P<0.05). 6. The new bone density was 73.0+/-8.6% in the control group and 66.6+/- 15.3% in the test group. There was no statistically significant difference between the two groups. These results suggest that the use of rhBMP-2 in 1-wall intrabony defects has significant effect on new cementum and new bone formation area, but doesn't have any significant effect on the prevention of junctional epithelium migration and new bone formation height.