Purpose: This prospective case series evaluated the use of a new synthetic resorbable membrane with autogenous bone, either alone or in combination with anorganic bovine bone-derived mineral, for horizontal ridge augmentation and subsequent implant placement. Materials and Methods: Particulated autogenous bone, either alone or in combination with anorganic bovine bone-derived mineral, was used for lateral ridge augmentation and covered with a new synthetic resorbable membrane (glycolide and trimethylene carbonate) to treat knife-edged ridges and prepare them for implant placement. Ridge measurements were obtained before and after augmentation, complications were recorded, and biopsy specimens were examined histologically. Results: Fifty-eight implants were placed in 22 patients with 25 surgical sites in knife-edged ridges. No complications were associated with this treatment. Clinical measurements revealed an average of 5.56 mm (± 1.45 mm) of lateral ridge augmentation after an average of 8.12 months (± 2.32 months) of graft healing. Clinically, all treated ridges were sufficient in width for subsequent implant placement. All implants have survived, with an average follow-up period of 45.88 months (± 12.43 months). Histologic analysis of the selected augmentation sites showed new bone formation and good incorporation of the bovine bone mineral particles. Conclusion: The high implant survival rate and the low complication rate show the potential of this technique for the treatment of horizontal augmentation of lateral ridges and the efficacy of the new resorbable synthetic membrane. Keywords: anorganic bovine bone-derived mineral, autogenous bone, guided bone regeneration, horizontal augmentation, resorbable membrane, sinus graft