Abstract: Mao Xiaofei, Fang Kai, Jia Qiannan, Qu Tao, Jin Hongzhong Department of Dermatology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China Corresponding author: Jin Hongzhong, Email: jinhongzhong@263.net 【Abstract】 Objective To evaluate safety and efficacy of a fractional microneedle radiofrequency device in the treatment of axillary osmidrosis. Methods A total of 24 patients with moderate to severe axillary osmidrosis were enrolled from Department of Dermatology of Peking Union Medical College Hospital between June 2015 and June 2016, and treated with the Body TiteTM fractional microneedle radiofrequency device for 1 session. Visual analogue scale （VAS） was used to evaluate the intensity of axillary odor in patients, 36-item short-form health survey （SF-36） to assess health-related quality of life（HRQoL）, and axillary skin tissues were resected for histopathological examination before and after the treatment. Results VAS showed that 22 of 24 patients achieved persistent remission for more than 12 weeks, and rates of decrease in odor score ranged from 50% to 100%. However, 1 patient experienced recurrence at 12 weeks after the treatment, and another 1 patient did not achieve clinical remission. SF-36 revealed that scores of social functioning （SF）, role-emotional （RE） and mental health（MH） scales were all significantly increased after the treatment［M（P0 - P100）: 100.00（62.00 - 112.50）, 100.00（33.30 - 110.00）, 68.00（48.00 - 80.00）, respectively］ compared with those before the treatment［77.50（62.50 - 100.00）, 66.67（33.30 - 100.00）, 55.00（48.88 - 72.00）, respectively, all P < 0.05］. Histopathological examination showed obvious degeneration and necrosis of sweat gland cells in 22 cases, and epidermal damages in 2 patients after the treatment. Unilateral upper-limb pain occurred in 1 case, and small-area burn-like skin changes were observed in 2 cases after the treatment. The postoperative recovery time ranged from 7 to 14 days. Conclusion The fractional microneedle radiofrequency device has shown high clinical response rate, good safety, and favorable application prospects in the treatment of axillary osmidrosis.