Abstract: Objective To evaluate the safety and effectiveness of CO2 fractional laser and fractional radio frequency for the treatment of atrophic acne scars. Methods Half face was randomly assigned to CO2 fractional laser with DeepFx mode or fractional radio frequency. The atrophic acne scars were firstly treated by pinpoint irradiations with one pass, the second scanning was performed for whole area. Three months after five treatment sessions with interval of 2 months, improvements of acne scars were scored using a quartile grading scale, and side effects were monitored at each follow-up visit. Results Twenty-eight patients completed the study. There was no significant difference of improvements on both sides of the acne scar. Hyperpigmentation was significantly higher in CO： fractional laser treatment side than fractional radiofrequency treatment side, the pain scores of CO2 fractional laser treatment side was less than the fractional radio frequency treatment side. No permanent hypopigmentation and scarring formation were observed. Conclusion Both CO2 fractional laser and fractional radio frequency can safely and effectively improve atrophic aene scars.

Key words: CO2 fractional laser, Fractional radio frequency, Atrophic acne scar