Background: A global increase in asthma and COPD incidence has occurred, the cause is unknown. One potential relationship that has yet to be explored is the interaction between blood pressure (BP) and lung function in children 5-17 years old. Our purpose is to assess the relationship between hypotension, hypertension, and lung function in children 5 to 17 years old. Methods: Participants were recruited from elementary and middle schools from 7 cities in northeastern China (N=6,797). BP was categorized into 3 groups: hypotensive (<5th percentile or <90mmHg if children >10 years), normotensive and hypertensive (>95th percentile) based on American Academy of Pediatrics standards. Spirometry measured lung function in forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), peak expiratory flow (PEF), and maximum mid expiratory flow (MMEF). Associations were assessed using logistic regression analysis. Results: Decreases in FVC , FEV1, PEF, and MMEF were noted in hypotensive children. Higher FVC, FEV1, PEF, and MMEF were noted among children ³ 10 with hypertension, while children <10 years, only had increased FVC compared to normotensive children. Statistically significant interactions between hypotension and PEF < 75% (OR:2.31; 95% CI: 1.17-4.23), were seen for children < 10 years. Conclusions: Our findings suggest that, in this study population, hypotension may be associated with decreased lung function, and the increased lung function may be associated with hypertension in children. Future studies are needed to confirm temporality as this is the first study to explore these relationships in children which requires in depth investigation.