Pneumothorax is a life-threatening complication during acute asthma attack. However, long-term risk of pneumothorax in asthmatic children remains unknown.In this retrospective cohort study, 333,657 children were defined as asthma cohort and a 1:1 matched non-asthma cohort were generated from 2000 to 2011. At the end of 2012, the incidence of pneumothorax in asthma and non-asthma cohorts and asthma to non-asthma hazard ratios (HRs) with confidence intervals (CIs) of pneumothorax were analyzed.The incidence of pneumothorax was 1.35-fold higher in the asthma cohort than that in the non-asthma cohort. The asthma to non-asthma HRs of pneumothorax were higher in children younger than 6 years (1.76, 95% CI: 1.21-2.57) and in girls (2.27; 95% CI: 1.23-4.16). The HRs of pneumothorax were higher in asthmatic children with more asthma-related out-patient clinic visits/per year (>5 visits; HR: 2.81; 95% CI: 1.79-4.42), more emergency department visits/per year (>4 visits; HR: 1.68; 95% CI: 1.02-2.78), and longer hospitalization days due to asthma (>4 days; HR: 3.42; 95% CI: 1.52-6.94) (P < .0001, the trend test).Asthmatic children had greater risk for pneumothorax, particularly in young children and in those with severe and uncontrolled asthma.Copyright © 2020 the Author(s). Published by Wolters Kluwer Health, Inc.