Objective In many developed countries, overweight and obesity prevalence seems to stabilise. The aim of this study was to determine trends between 1999 and 2011 in overweight and obesity prevalence, and mean Body Mass Index (BMI) z-score in Dutch, Turkish, Moroccan and Surinamese South Asian children in the Netherlands. Design A cross-sectional population-based study with 136 080 measurements of height and weight of 73 290 children aged 3–16 years. BMI class and BMI z-score were determined with the latest International Obesity Taskforce (IOTF) criteria, with overweight defined as an adult BMI equivalent ≥25 and obesity ≥30. Time trends per year were analysed using logistic and linear regression analyses. Results The prevalence of overweight in Dutch children declined from 13% to 11% (OR 0.960; 95% CI 0.954 to 0.965), but increased in Turkish children from 25% to 32% (OR 1.028; 95% CI 1.020 to 1.036). In Moroccan and Surinamese South Asian children, overweight rates were stable, but obesity prevalence decreased (OR 0.973; 95% CI 0.957 to 0.989, OR 0.964; 95% CI 0.943 to 0.985, respectively) as well as the mean BMI z-score (B=−0.010; 95% CI −0.014 to −0.006, B=−0.010; 95% CI −0.016 to −0.004). In Turkish children, trends limited to the period 2007–2011 showed no statistically significant relationship for all outcome measures. Conclusions The decrease in obesity prevalence in Dutch, Moroccan and Surinamese South Asian children suggests that overweight children became less adipose. The stabilising trend in overweight and obesity prevalence in Turkish children since 2007 may signify a levelling off for this ethnic group.