OBJECTIVE: To record the prevalence of overweight and obesity in urban primary-school children in relation to several socio-economic and demographic factors. DESIGN: Cross-sectional. SETTING/SUBJECTS: A representative sample of 729 schoolchildren (379 male and 350 female), aged 9-13 years, stratified by parental educational level, was examined in the urban region of Athens. Weight and height were measured using standard procedures. The International Obesity Task Force thresholds were used for the definition of overweight and obesity. Several socio-economic and demographic data and the child's 'popularity' score were also recorded with specifically designed standardized questionnaires. RESULTS: The prevalence of overweight and obesity was 29·6 % and 11·1 %, respectively. Annual family income of € 12,000-20,000 (OR = 1·58), residence ownership (OR = 1·63) and the grandmother as the child's primary caregiver (OR = 1·38) were significantly associated with higher odds of childhood overweight and obesity. Non-Greek parental nationality (OR = 0·72) and higher 'popularity' scores of children (OR = 0·42) were significantly associated with lower odds of overweight and obesity. The grandmother as the child's primary caregiver and an annual family income of € 12,000-20,000 remained significantly associated with childhood overweight and obesity after adding all significant correlates of childhood overweight and obesity observed at the bivariate level in a multivariate regression model (OR = 1·51 and 1·61, respectively). CONCLUSIONS: Among family income, residence ownership, child's primary caregiver, parental nationality and popularity scores that were identified as significant correlates of childhood overweight and obesity at the bivariate level, lower family income and grandmother as the child's primary caregiver were the only factors that remained significantly associated with childhood overweight and obesity at a multivariate level.