Using guided tissue regeneration for treatment of molars class II furcation involvement is more predictable, but less predictable for class III furcation involvement, especially it is more difficult for maxillary class III furcation involvement due to three furcations. This case report is using Gore-tex periodontal membrane combined with demineralized freeze dried bone allograft for the treatment of maxillay first molar class III furcation invo lvement. Buccal and mesial furcation defects was completely covered with new periodontal tissue when the membrane was removed after five weeks of GTR. The improvement of periodontal probing data and increasing bone density by X-ray film were found after one year and six months. The condition is stab le after 2 years and six months follow-up.