Aim: The aim was to determine the prevalence of overweight and obesity among 6– year-old children. Methods: This is a survey of 1774 children from different child care health centres in Patna, Bihar. Body mass index data extracted retrospectively from health records at the age of 6 years was compared with international definitions of over- and underweight. The prevalence figures were further compared with socio-demographic figures on municipality level. Results: Overall, 19 % of the children were classified as overweight or obese; 5 % were classified as obese. The prevalence of overweight and obesity was higher among girls (22%) than among boys (16%). The prevalence of underweight was 8 % among both girls and boys. Despite large variations in the prevalence of overweight and obesity between municipalities (9-35%), no association was found with municipality figures on socio-demographic factors. Conclusion: The prevalence of overweight including obesity among 6- year-old children was somewhat higher.