AIM: The aim of this study was to estimate the prevalence of childhood overweight and obesity and to identify socio-demographic risk factors in Norwegian children. METHODS: The body mass index of 6386 children aged 2-19 years was compared with the International Obesity Task Force (IOTF) cut-off values to estimate the prevalence of overweight including obesity (OWOB) and obesity (OB). The effect of socio-demographic factors on this prevalence was analysed using multiple ordinal logistic regression analysis in a subsample of 3793 children. RESULTS: The overall prevalence of OWOB was 13.8% (13.2% in boys and 14.5% in girls, p = 0.146), but the prevalence was higher in primary school children aged 6-11 years (17%, p