Objective: Objective To explore the role of the Er: YAG laser in periodontal surgery. Methods : Twenty patients with chronic periodontitis in two quadrants were selected for this study. One quadrant was subjected to pure periodontal flap surgery, whereas the other was subjected to flap surgery with an adjunctive Er: YAG laser. The preoperative and 3- and 6-month postoperative clinical parameters, including the probing depth, clinical attachment level, gingival recession, plaque index, gingival index and tooth mobility, were recorded. Results: Significant differences were not observed between the open flap surgery + Er: YAG laser-assisted treatment group and the open flap surgery group except for the gingival index after 3 months (0.36 ± 0.26 vs. 0.58 ± 0.29, t=3.831, P < 0.001) and 6 months (0.60 ± 0.23 vs. 0.83 ± 0.22, t=4.013, P < 0.001). Conclusion Er:YAG as an auxiliary treatment for periodontal flaps, does not significantly reduce the depth of periodontal pockets, nor could it improve the clinical adhesion level and the gingival recession, but it can improve the recovery of gingival inflammation and accelerate the healing of tissue.