Objective:To compare the clinical efficacy and safety of single microneedle radiofrequency versus photodynamic therapy in the treatment of inflammatory lesions of moderate and severe facial acne vulgaris.Methods:Sixty patients with moderate to severe facial acne vulgaris were retrospectively collected from Guangzhou Institute of Dermatology between December 2021 and July 2022, including 30 patients who had received single microneedle radiofrequency treatment, and 30 patients who had received photodynamic therapy. There were no significant differences in the age, gender distribution, and severity of acne between the two groups (all P > 0.05). The patients in the microneedle radiofrequency group were treated with single microneedle radiofrequency once every 4 weeks for 2 sessions; those in the photodynamic therapy group received aminolevulinic acid-based photodynamic therapy once every 2 weeks for 3 sessions; patients in both groups were still treated with oral doxycycline for 8 weeks. After 8-week treatment, the efficacy, pain severity and incidence of adverse reactions were compared between the two groups. Statistical analysis was carried out by using chi-square test, two independent samples t-test and Mann-Whitney U test. Results:After 8-week treatment, there was no significant difference in the response rate between the microneedle radiofrequency group (93.33%, 28/30) and photodynamic therapy group (86.67%, 25/30; χ2 = 0.74, P = 0.389). No significant difference was observed in the pain severity score between the microneedle radiofrequency group (4.80 ± 2.08) and photodynamic therapy group (4.13 ± 1.86, t = 1.32, P = 0.194), and there was also no significant difference in the pain degree between the two groups ( Z = -1.13, P = 0.260). In the microneedle radiofrequency group, burning sensation occurred in 3 cases (10.00%), swelling and pain in 4 (13.33%), erythema in 2 (6.67%), and dryness and desquamation in 2 (6.67%), and no reactive acne or hyperpigmentation was observed; in the photodynamic therapy group, burning sensation occurred in 10 cases (33.33%), swelling and pain in 9 (30.00%), erythema in 8 (26.67%), reactive acne in 11 (36.67%), hyperpigmentation in 2 (6.67%), and dryness and desquamation in 11 (36.67%). Compared with the photodynamic therapy group, the microneedle radiofrequency group showed significantly decreased incidence rates of burning sensation, erythema, reactive acne, and dryness and desquamation ( χ2 = 4.81, 4.32, 13.47, 7.95, respectively, all P < 0.05) ; there was no significant difference in the incidence rates of swelling and pain as well as hyperpigmentation between the two groups ( χ2 = 2.46, 2.07, respectively, both P > 0.05) . Conclusion:Single microneedle radiofrequency showed marked efficacy equivalent to that of photodynamic therapy in the treatment of moderate to severe facial acne vulgaris, but higher safety, providing more clinical treatment options for moderate to severe facial acne vulgaris.