Four clinical centers, using the Brånemark System and with personnel trained in the use of Gore-Tex Augmentation Material (GTAM), participated in a prospective study of 45 patients 18 to 83 years of age. A total of 55 implants were placed with membranes because of local bony defects (fenestration or dehiscence). Dehiscence and fenestration defects were evaluated as one group. The mean initial defect height was 4.7 mm (SD = 3.0). After healing, the remaining defect height was reduced to 1.1 mm (SD = 2.3). The decrease in surface exposure was significant. Complications were primarily attributed to exposure of six membranes during the early healing period. The cumulative survival rate was 84.7% in maxillae and 95.0% in mandibles after 2 years of follow-up. The surgical application of GTAM to produce bone in localized bony defects around oral implants seems to be a predictable method that may reduce the need for extensive augmentation surgery in patients with insufficient jaw bone volume. Keywords: bone regeneration, ePTFE, implants, membranes