Objective:To derive age and sex-specific reference values for waist circumference(WC) for Han Chinese children and adolescents living in Chongqing and to provide data for the study of excess central adiposity in the group.Methods:A school based

cross-sectional study was conducted in the Chongqing in October 2003 and April 2004.A total of 7 326(49.2% boys)Han students aged 5～17 years were recruited from 15 primary schools and 9 secondary schools.Anthropometry was used in standard procedures.The LMS method was used to construct smoothed WC percentile curves.Overweight and obesity were defined by the criteria of international obesity task force(IOTF) and the working group on obesity in children.Results:Before age 15

WC of boys and girls was increased with age;after 15 years of age

the curve flattened;in the overall trend

most of the percentile of the mean waist circumference of the boys of all ages was greater than that of girls.A comparison of the waist circumference at 50 percentile and 90 pecentile between Chongqing

Xingjiang and Hong Kong revealed the data in this study were similar to the data in Xingjiang

and higher than those in Hong Kong in both boys and girls.Conclusion:We have constructed WC percentile curves for Han Chinese children and adolescents living in Chongqing.Our measurements are based on a student population with a relatively high rate of overweight and obesity.These data will provide a point of reference for future studies measuring the prevalence of overweight and obesity in China.