Reduced lung function has been observed in adults with excess adiposity; however, in children, the relationship between adiposity and lung function is not clearly understood. A sample of 1,583 children, less than 18 years of age, from the Canadian Health Measures Survey (CHMS) was used to examine the associations of various anthropometric and skinfold measures with lung function parameters. The mean age of the sample was 12.15 (0.096). In normal weight boys, body mass index (BMI) was positively associated with forced vital capacity (FVC), FEV0.75 and FEV1; while in overweight or obese boys, waist circumference (WC) and waist-to-hip ratio showed inverse correlations with pulmonary function measures. Similarly, in normal weight girls, BMI and WC had positive associations with lung function measures but no inverse effect of adiposity was observed in overweight or obese girls. Skinfold analysis showed that only triceps skinfold had a significant inverse association with FVC and borderline significant associations with FEV0.75 and FEV1 in normal weight boys; while in overweight or obese boys, all the skinfold indicators displayed inverse correlations with lung function. The best predictor of lung function was triceps skinfold with βstd=-0.3869 for FVC, -0.3496 for FEV0.75 and -0.3668 for FEV1. No inverse correlations between skinfolds and lung function were observed in girls. Adiposity had differing effects on respiratory function that were dependent on sex and BMI group with the most significant effect on the overweight or obese boys. The most important indicator of adiposity in boys with BMI <30 kg/m2 was triceps skinfold. In girls, adiposity was not associated with poor lung function.