The treatment of a peri-implant infrabony defect is difficult because of contamination of the implant surface and adjacent tissues. This case series addresses the ability of a carbon dioxide (CO2) laser to decontaminate failing implants in 15 patients. Clinical and radiologic data are presented with regard to using the laser in combination with bone grafting and a barrier. Augmentation with autogenous bone grafting material (n = 10) or a xenogenic bone grafting material (BioOss) (n = 9) was used, and bone grafts were covered with a collagen membrane. Clinical and radiologic parameters were evaluated postoperatively. After an observation period of 27 months (± 17.83), almost complete bone fill in the peri-implant defect was accomplished. These preliminary clinical and radiologic findings suggest that decontamination of the implant surfaces with the CO2 laser in combination with augmentative techniques can be an effective treatment method for periimplantitis.