Van Emmerick and colleagues from the Netherlands report on a nationwide prospective surveillance study to assess the prevalence of cardiovascular risk factors in severely obese children and adolescents, The study was carried out from July 2005 to July 2007 where paediatricians were asked to report all new cases of severe obesity in 2–18-year-old children to the Dutch Paediatric Surveillance Unit. Severe obesity was defined by gender and age-dependent cut-off points for BMI Paediatricians were asked to complete a questionnaire for every severely obese child regarding socio-demographic characteristics and cardiovascular risk factors (blood pressure, fasting blood glucose and lipids). 500 children with newly diagnosed severe obesity were reported and cardiovascular risk factor data were available in 255 children and young people with severe obesity. 67% had at least one cardiovascular risk factor (56% hypertension, 14% high blood glucose, 0.7% type 2 diabetes and up to 54% low HDL-cholesterol). Remarkably, 62% of severely obese children aged ≤12 years already had one or more cardiovascular risk factors. The authors conclude that a high number (2/3) of severely obese children have cardiovascular risk factors and that internationally accepted criteria for defining severe obesity and guidelines for early detection and treatment of severe obesity and comorbidity are urgently needed.