Introduction - The World Health Organization classifies obesity as a global epidemic; in France, this condition is on the rise among children. It has been shown that childhood overweight is linked to parents’ socioeconomic status: the objective of this analysis is to verify this link and to study its determinants in Alsace using data from the medical examination administered upon admission to elementary school. Method - A cross-sectional study was conducted among children in their final year of preschool. The criterion for overweight status is Body Mass Index (BMI) compared to the thresholds established by the International Obesity Task Force in 2000; the socioeconomic criterion is the classification of the parents according to the nomenclature of occupations and socio-professional categories. A multivariate analysis using logistic regression was performed. Results - 4,460 students were examined; the prevalence of overweight (including obesity) was 15.1% [13.8%; 16.5%]; it was 19.7% for children of manual workers, 11.2% for children of managers, and 14.9% for others (p<0.001). This difference remains significant after adjusting for other risk factors: having blue-collar parents is associated with an adjusted odds ratio of 1.65 (p=0.001), with the reference category being parents in managerial positions. Discussion-Conclusion - A social gradient of overweight (including obesity) is observed among six-year-old children in Alsace; this gradient cannot be reduced to differences in individual behaviors. Reducing social inequalities in overweight therefore requires a comprehensive health promotion approach. (R.A.)