PURPOSE: This study was done to identify the level of knowledge and practice of self-management on asthma of school-aged children and to provide data for the development of an intervention program to improve self-management on asthma. METHODS: The participants were 100 school-aged children who were treated currently for asthma in J city located in G province. Data were collected from 25th August to 30th October 2014. RESULTS: The mean scores were 14.37 of 20 for self-management knowledge (percentage of correct answer 71.9%), 21.65 of 30 for self-management practice. There were significant differences in knowledge according to grade, diagnosed age, food allergy, education on asthma and hardship in school life, and in practice according to gender and economic status, hardship in school life and experience of first-aid on asthma. There were positive correlations between knowledge and practice. CONCLUSION: Results indicate that school-aged children' knowledge and practice in self-management of asthma were not sufficient enough to perform accurate management of asthma. Therefore, to improve self-management ability of school-aged children to manage effectively asthma, educational strategies that focus on increasing knowledge need to be developed.