Objective: To determine trends in the prevalence of overweight and obesity in children in the city of The Hague (the Netherlands) from 1999 through 2007. Design: Population-based study of a series of cross -sectional assessments of height and weight from electronic health records. Setting: Child Health Care of Municipal Health Service The Hague. Participants: 50 961 children, aged 3-16 years, with Dutch (59%), Turkish (17%), Moroccan (13%) or Surinamese South Asian (11%) ethnicity, representative of the four major ethnic groups in The Hague, with 85 234 weight and height measurements recorded in the period 1999-2007. Main outcome measures: (Trends in) prevalence of overweight (excluding obesity) and obesity as defined by the International Obesity Taskforce (IOTF) cut-off points, using logistic regression with year as independent variable. Results: From 1999 through 2007 there was a decrease in the prevalence of overweight in Dutch girls from 12.6% to 10.9% (odds ratio [OR]=0.96; 95% Confidence Interval [CI]= 0.95-0.98) and an increase in Turkish boys from 14.6% to 21.4% (OR=1,08; 95%CI:1.04-1.11). Obesity prevalence rose significantly in Turkish boys from 7.9% to 13.1% (OR=1.04; 95%CI:1.01-1.06) and in Turkish girls from 8.0% to 10.7% (OR=1.04; 95%CI:1.01-1.08). Dutch boys, and Moroccan and Surinamese South Asian boys and girls showed no significant trends. Conclusions: The declining prevalence of overweight in Dutch girls may indicate a turning point in the trend from past decades in the Netherlands. However, in Turkish children prevalence of overweight as well as obesity is high and increasing. Further public health actions remain necessary, especially for Turkish children.