Abstract: Wang Chen, Han Xiaofeng, Xu Zigang, Ma Lin Department of Dermatology, Beijing Children′s Hospital, Capital Medical University, Beijing 100045, China Corresponding author: Ma Lin, Email: bch_maleen@aliyun.com 【Abstract】 Objective To investigate the efficacy and safety of ultrapulsed fractional CO2 laser in the treatment of porokeratosis in children. Methods Clinical data were collected from 9 children with porokeratosis in the Department of Dermatology of Beijing Children′s Hospital from January 2014 to December 2015, and analyzed retrospectively. These patients were all treated with ultrapulsed fractional CO2 laser in a dynamic superficial stripping （Active FX） mode. The initial energies were 100, 200 and 300 mJ/cm2, and the frequencies ranged from 100 to 300 Hz. Before and after the treatment, as well as during the follow-up, confocal laser scanning microscopy was used to evaluate the severity and recovery of skin lesions. Results Of the 9 patients, 7 were male, and 2 were female. Their average age was 4.19 ± 3.97 years. After the treatment with ultrapulsed fractional CO2 laser, all of the patients were considered to be cured based on the clinical standard. Some adverse reactions such as erythema, edema and erosion occurred in the 9 patients immediately after the treatment, but all completely regressed within 3 - 7 days. At 3, 6 and 12 months after the treatment, no scars or skin discoloration was observed. The average duration of follow-up was 1 year, and the longest duration of follow-up was 2 year and 4 months. No relapse occurred during the follow-up. Conclusion Ultrapulsed fractional CO2 laser is effective and safe for the treatment of porokeratosis in children.