AIM To evaluate the outcomes of conventional periodontal maintenance therapy on patients surgically treated for peri-implantitis. MATERIAL AND METHODS 27 patients with 149 dental implants were monitored during 5 years every 6 months. At each recall visit, the prostheses were removed to have proper access for implant examination and supra- and sub-gingival instrumentation. Sub-gingival instrumentation was performed using an ultrasonic instrument with under 0.12% chlorhexidine irrigation. RESULTS At baseline (6 months following peri-implant surgery), 149 implants (78 not treated and 71 treated) were available for analysis. Of the 71 treated implants, 43 presented healthy peri-implant condition, while 28 had residual peri-implant pockets either of 4-5 mm or ≥ 6 mm associated with bleeding on probing/suppuration. The longitudinal evaluation revealed that the plaque and the bleeding index scores were low during the entire follow-up period, and healthy peri-implant conditions were maintained for both the 78 non-treated and the 43 treated "healthy" implants. Of the 28 implants with residual pockets, nine showed clinical attachment loss during the 5-year follow-up. Thus, of 71 treated implants, probing attachment loss occurred in only in 9 (13%) of the implants in four patients during the 5-year period. The presence of residual pockets at three or four sites of the implants (circumferential type of pockets) was frequently associated with increased probing pocket depth (PPD) and attachment loss, while this was not the case for implants with the presence of pockets at one or two sites only (site specific). CONCLUSION In patients with a high standard of oral hygiene and enrolled in a recall system every 6 months, the peri-implant conditions obtained following peri-implant surgery were maintained stable for the majority of subjects and implants during a 5-year period. Presence of residual pockets around the circumference of the implants seemed to be a high predictor for disease progression.