In adults abdominal obesity is related to lung dysfunction and waist circumference (WC) predicts pulmonary function. It is not known how WC affects pulmonary function in children. A cross-sectional study of 718 children 6-17 years of age was conducted in a rural community to determine the predictability of WC for pulmonary function in children. Height, weight, WC, and pulmonary function were measured. Multivariate analysis was conducted. WC was positively associated with FVC and FEV(1) and was more strongly associated with FVC than with FEV(1). Increase in WC significantly predicted a reduction in FEV(1)/FVC. After adjustment for sex, age, and height, an increase of 1 cm for WC was associated with an increase of 7 ml of FVC and 4 ml of FEV(1), and with an increase of 4 ml of FVC and 2 ml of FEV(1) with an additional adjustment for weight. Height and weight were not significantly associated with FEV(1)/FVC. WC but not body mass index predicted a decline of FEV(1)/FVC. WC had a larger impact on FVC than FEV(1). WC, but not BMI, was negatively associated with FEV(1)/FVC in children.