An effective treatment regime for peri-implantitis (P-I) should include disinfection and regeneration of peri-implant tissues. Twenty consecutive patients exhibiting 23 P-I implants with 84 deep (≥ 6 mm) defects were treated using an Er:YAG laser for implant surface decontamination, removal of defect granulomatous tissues, and grafting therapy for bony defect resolution. Probing pocket defects (PPD) ≥ 6 mm (deep probing depths) before surgery were reduced on average to approximately 3.5 mm at 12 months. Probing depths 6 mm (shallow probing depths) remained stable (mean PPD 3.2 mm at 12 months). Radiographs indicated PPD reductions were achieved along with peri-implant defect fill.