Abstract: Objective To investigate the efficacy of ablative fractionated erbium: yttrium aluminum garnet （Er: YAG） laser in facial acne scars and enlarged pores. Methods Forty-one patients with mild to moderate pitted acne scars and 23 patients with enlarged pores were treated with 81 （9 × 9） bits of facula for 3 to 5 sessions at an interval of 1 month. For acne scars, the pulse duration was medium to long, energy at 800 to 1200 mJ, and number of stacking passes 4 to 8; for enlarged pores, the pulse duration was medium, energy at 800 to 1000 mJ and number of stacking passes 2 to 4. The clinical improvement was evaluated by 2 blinded dermatologists. Meanwhile, the satisfaction rate was self-assessed by patients. Three-dimensional （3D） microtopography imaging system was used to evaluate the improvement in surface roughness. Results The efficacy reached 82.93% and 86.96% for acne scars and enlarged pores, respectively. The satisfaction rate was 88.80% and 91.30% in patients with acne scars and those with enlarged pores, respectively. After treatment, the Ra and Rz values, as the indicators of roughness, decreased by 18.74% and 21.01%, individually （P < 0.001） in 11 patients including 6 with acne scars and 5 with enlarged pores. Conclusion Ablative fractionated Er:YAG laser can efficiently resurface pitted acne scars and shrink enlarged pores.

Key words: ablative fractionated Er:YAG laser, scar