Objective: To evaluate the short-term outcome of regenerative surgery for peri-implantitis therapy. Methods: From March 2018 to January 2019, 9 patients with 10 implants who suffered from peri-implantitis were included in the present research. Vertical bone defect at least 3mm in depth with 2 or more residual bone walls was confirmed around each implant by radiographic examination. Restorations were replaced by healing abutments on 3 implants with the consent of the patients. Guided bone regeneration surgery was performed after a hygienic phase. During surgery, full thickness flaps were elevated on both buccal and lingual aspects. Titanium curette was used for inflammatory granulation tissue removal and implant surface cleaning. The implant surface was decontaminated by chemical rinsing with 3% hydrogen peroxide solution. After being thoroughly rinsed with saline,the bone substitutes were placed in bone defects which were covered by collagen membranes. 6 months after non-submerged healing, the clinical parameters including peri-implant probing depth (PD, distance between pocket bottom and peri-implant soft tissue margin) and radiographic bone level (BL, distance form implant shoulder to the first bone-to-implant contact) were used to evaluate the regenerative outcome. PD was measured at six sites (mesial, middle and distal sites at both buccal and lingual aspects) around each implant, and BL was measured at the mesial and distal surfaces of each implant on a periapical radiograph. Results: The deepest PD and largest BL of each implant ranged from 6-10 mm and 3.2-8.3 mm respectively. All the implants healed uneventfully after surgery. The mean peri-implant PD at baseline and 6 months after surgery were (6.2±1.4) mm and (3.1±0.6) mm respectively, and a mean (3.0±1.5) mm radiographic bone gain was observed, P<0.01. Treatment success was defined as: no sites with residual PD≥6 mm, no bleeding on probing, and BL elevation of at least 1 mm. Nine implants from 8 patients fulfilled the success criteria. Residual pockets with 6 mm in depth and bleeding on probing could be detected in only one implant. Conclusion: Within the limitation of the present research, guided bone regeneration surgery can be used for the treatment of bone defect that resulted from peri-implantitis. Significant PD reduction and radiographic bone gain can be obtained after 6 months observation.