This article presents two methods of guided tissue regenertion with polytetrafluoroethylene membranes that promote extensive regeration of periodontal supporting tissue around several adjacent teeth. These techniques are effective in patients with profound marginal periodontitis and advanced horizontal and vertical bony defects affecting large areas of the mouth. In method A, the goal of regeneration is reached by covering the defect with a row of seveal ovelapping membranes. However,the favorable results obtained with this method had to be weighed against various problems concerning the surgical procedure and wound healing. These unsolved difficulties prompted the development of method B, in which only one large membrane is used. After appropriate relieving incisions are made in the membrane, it is placed into the interdental space and thus able to cover and extensive periodontal defect. during the last 4 years, favorable results have been obtained with both new methods of guide tissue regeneration.