BACKGROUND Lab studies have suggested that ubiquitous phthalate exposures are related to obesity, but relevant epidemiological studies are scarce, especially for children. OBJECTIVE To investigate the association of phthalate exposures with body mass index (BMI) and waist circumference (WC) in Chinese school children. METHODS A cross-sectional study was conducted in three primary and three middle schools randomly selected from Changning District of Shanghai City of China in 2011-2012. According to the physical examination data in October, 2011, 124 normal weight, 53 overweight, and 82 obese students 8-15 years of age were randomly chosen from these schools on the basis of BMI-based age- and sex-specific criterion. First morning urine was collected in January, 2012, and fourteen urine phthalate metabolites (free plus conjugated) were determined by ultra-performance liquid chromatography coupled to tandem mass spectrometry. Multiple linear regression was used to explore the associations between naturally log-transformed urine phthalate metabolites and BMI or WC. RESULTS The urine specific gravity-corrected concentrations of nine urine phthalate metabolites and five molar sums were positively associated with BMI or WC in Chinese school children after adjustment for age and sex. However, when other urine phthalate metabolites were included in the models together with age and sex as covariables, most of these significant associations disappeared except for mono (2-ethylhexyl) phthalate (MEHP) and monoethyl phthalate (MEP). Additionally, some associations showed sex- or age-specific differences. CONCLUSIONS Some phthalate exposures were associated with BMI or WC in Chinese school children. Given the cross-sectional nature of this study and lack of some important obesity-related covariables, further studies are needed to confirm the associations.