CONCLUSIONS OBJECTIVE To evaluate the associates of obesity and overweight in 7-year-old children. METHODS Cross-sectional study. METHODS 855 children out of all 1278 school beginners in the city of Oulu, Northern Finland. METHODS A questionnaire to be filled in by parents was delivered by the school nurses to 1278 children. The child's eating habits, dietary intake and physical activity patterns were enquired about. There were also questions about the household and parents' level of education and physical activity. Overweight and obesity were defined by BMI according to internationally accepted criteria. The χ(2) test was used to evaluate the significance of the differences between normal and overweight children. Multivariate logistic regression model was used to find the most predictive variables associated with overweight and obesity. The final models are reported using odds ratios (ORs) and their 95% confidence intervals (CI). RESULTS The number of responders was 855 (66.9%). The prevalence of overweight was 16.7% and that of obesity 4.9%. Fifty-seven percent of the parents who had an overweight or obese child 7-year-old did not recognise their child's overweight. The factors associated with obesity were: mother's obesity (OR 13.04, CI 2.81-60.53), low physical activity (OR 10.95, CI 3.28-36.50), skipping breakfast (OR 10.12, CI 1.81-56.63), habitual overeating (OR 9.35, CI 2.58-33.82), father's overweight (OR 5.89, CI 1.23-28.10) and mother's age over 40 years (OR 2.91, CI 1.09-7.80). CONCLUSIONS This cross-sectional study promotes the importance of child's eating behaviour and family's eating patterns. Parents should be helped to recognise their child's overweight, and educational strategies should be targeted at both children and their parents. Avoiding inactivity is essential in preventing obesity in children.