Purpose: The purpose of this systematic review was to evaluate long-term outcomes of regenerative procedures for treating peri-implantitis. Materials and Methods: Electronic searches of five databases and hand searches of journals were performed to identify human trials that had treated more than 10 periimplantitis lesions using a regenerative approach with a follow-up period of at least 36 months. To meet the inclusion criteria, studies had to report at least one of the following parameters: radiographic bone fill (RBF), probing depth (PD) reduction, clinical attachment level gain, bleeding on probing reduction, and mucosal level gain. The pooled weighted mean and the 95% confidence interval (CI) of each variable were estimated. Results: The searches yielded 1,412 records, and after evaluating titles, abstracts, and full texts, 5 case series and 1 controlled trial were included for quantitative data synthesis. Meta-analysis of the studies for the amount of RBF revealed a weighted mean of 2.41 mm (range, 1.46 to 3.30 mm) with 95% CI. For PD reduction, the weighted mean was 3.06 mm (range, 1.24 to 5.21 mm). Conclusion: There is limited evidence in the literature reporting long-term results of the regenerative approach for treating peri-implantitis. Within the limits of this meta-analysis, regenerative treatment of peri-implantitis resulted in a mean radiographic defect fill of 2.41 mm after a minimum healing time of 36 months. However, this finding must be interpreted with caution, since it is difficult to discern between grafting material and newly formed bone. Keywords: alveolar bone reconstruction, dental/oral implants, evidence-based dentistry, guided bone regeneration, peri-implant repair, tissue engineering