Present investigation was designed to evaluate the regenerative potential of the periodontal ligament tissue in degree III furcation defects. The upper 2. and 3. premolar teeth of 3 dogs were used. Periodontal breakdown was induced around the teeth by experimental periodontitis model. After the breakdown occurred, mucoperiostal flaps were elevated and granulation tissue removed. The roots were curretted and cementum of the periodontitis involved parts of the roots was removed. The resorbable material was trimmed to approximate size needed to cover the root surfaces. The material provisionally adapted to the both buccal and palatinal root surfaces and flaps were sutured. After 42 days of post operative period histological examination of experimental and control groups showed that chances of obtaining new connective tissue attachment may be enhanced in treatment of Cl III furcation defect by Guided Tissue Regeneration.