Objective: To assess the prevalence of overweight and obesity in children living in the Netherlands and compare the findings with the Third and Fourth National Growth Studies carried out in 1980 and 1997, respectively. Design and methods: Data were obtained from the child health care system. International cut-off points for body mass index (BMI) were used to determine overweight and obesity. Cases were weighted for ethnicity and municipality size in such a way that the sample matched the distribution in the general population. The LMS method was used to calculate the age-related distribution of BMI, and the prevalence was calculated from the fitted distribution. Patients: Data on 90 071 children aged 4–16 years were routinely collected by 11 community health services during 2002–2004. Results: On average, 14.5% of the boys and 17.5% of the girls were overweight (including obesity), which is a substantial increase since 1980 (boys 3.9%, girls 6.9%) and 1997 (boys 9.7%, girls 13.0%). Similarly, 2.6% of the boys and 3.3% of the girls aged 4–16 years were obese, which is much higher than in 1980 (boys 0.2%, girls 0.5%) and 1997 (boys 1.2%, girls 2.0%). At the age of 4, 12.3% of the boys and 16.2% of the girls were already overweight. Conclusions: The prevalence of overweight and obesity in the Netherlands is still rising, and at an even faster rate than before. Evidence-based interventions are needed to counter the obesity epidemic, and there is an urgent need for pre-school intervention programmes.