The purpose of this study was to investigate the effect of porous xenographic bone graft (Bio-Oss) with a collagen barrier membrane (Bio-Gide) on formation new cementum and new bone in experimental intrabony defects of dogs. The intrabony defects were treated by either guided tissue regeneration with the collagen membrane (control group) or the collagen membrane with the porous bone mineral graft (experimental group). After 8 weeks, the animals were sacrificed and the tissues were histologically examined. New cementum with inserting collagen fibers was observed on the exposed surfaces in both groups. The amount of new bone was significantly greater in the group using the bone graft with the membrane than in the control group. The use of the collagen barrier membrane in combination with the porous bone graft material may enhance new bone and cementum formation.