Journal of Research in Medical Sciences1735-199516920110915Comparison of Q-Switched 1064-nm Nd: YAG laser and fractional CO2 laser efficacies on improvement of atrophic facial acne scar71047104ENAliAsilianEliasSalimiResident, Department of Dermatology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran. eliassalimi@yahoo.comGitaFaghihiFaridehDehghaniNabetTajmir RiahiSayed MohsenHosseini201104192011090320110612BACKGROUND: Acne scarring is treatable by a variety of modalities. Ablative carbon dioxide laser (ACL), while effective, is associated with undesirable side effect profiles. Newer modalities using the principles of fractional photothermolysis (FP) produce modest results than traditional carbon dioxide (CO2) lasers but with fewer side effects. A novel ablative CO2 laser device use a technique called ablative fractional resurfacing (AFR), combines CO2 ablation with a FP system. This study was conducted to compare the efficacy of Q-switched 1064-nm Nd: YAG laser and that of fractional CO2 laser in the treatment of patients with moderate to severe acne scarring. METHODS: Sixty four subjects with moderate to severe facial acne scars were divided randomly into two groups. Group A received Q-Switched 1064-nm Nd: YAG laser and group B received fractional CO2 laser. Two groups underwent four session treatment with laser at one month intervals. Results were evaluated by patients based on subjective satisfaction and physicians’ assessment and photo evaluation by two blinded dermatologists. Assessments were obtained at baseline and at three and six months after final treatment. RESULTS: Post-treatment side effects were mild and transient in both groups. According to subjective satisfaction (p = 0.01)  and physicians’ assessment (p < 0.001), fractional  CO2 laser was significantly more effective than Q- Switched 1064- nm Nd: YAG laser. CONCLUSIONS: Fractional CO2 laser has the most significant effect on the improvement of atrophic facial acne scars, compared with Q-Switched 1064-nm Nd: YAG laser. KEYWORDS: Laser, Acne, Scar.