RATIONALE: Asthma and allergic rhinitis are prevalent in community, and may affect health-related quality of life differently in children. The author aimed to measure health-related quality of life across asthma and/or allergic rhinitis in school pupils by the PedsQL™ questionnaire, a generic measure. METHODS: A cross-sectional survey of 1,500 pupils, aged 8-16 years, in 3 schools located in Prathumthani province of Thailand was performed. Diagnosis of asthma and allergic rhinitis was performed using the International Study of Asthma and Allergies in Childhood (ISSACC) questionnaire. Health-related quality of life, consisting of 4 domains, was examined by the self-administered PedsQL™ questionnaire. RESULTS: There were 10.7 and 35.0 percents of school pupils having asthma and allergic rhinitis respectively. Of 1,500 participants, the mean total score of the health-related quality of life was 76.9 (SD=11.3) whereas the mean total scores of the health-related quality of life among asthmatic and allergic rhinitis pupils were 68.1 (SD=8.3) and 73.9 (SD=11.4) respectively. The mean scores of physical, emotional, social, and school functioning among asthmatic pupils were significantly less than those of non asthmatic of 5.0 (p<0.001), 13.2 (p<0.001), 5.6 (p<0.001), and 7.8 (p<0.001) respectively. The mean scores of physical, emotional, social, and school functioning among allergic rhinitis pupils were less than those of non allergic rhinitis of 2.0 (p=0.008), 3.6 (p<0.001), 0.7 (p=0.495), and 0.4 (p=0.692) respectively. CONCLUSIONS: Asthma significantly affects health-related quality of life among Thai pupils especially on emotional dimension whereas allergic rhinitis has less effect on health-related quality of life.