The aims of the present work were to investigate whether dietary habits are associated with socio-economic status (SES), and if they modify the relationship between SES and CVD risk factors, in a sample of men and women free from known CVD.This population-based study was carried out in the province of Attica, where Athens is a major metropolis. During 2001-2002, information from 1,528 men (18-87 years old) and 1,514 women (18-89 years old) was collected (75 % participation rate). Among several sociodemographic, clinical and biological factors, adherence to the Mediterranean diet was assessed by a special diet score (Mediterranean Diet Score, MDS) that incorporated the inherent characteristics of this traditional diet. CVD risk factors were examined across the participants' educational level and annual income that defined their SES.Low SES groups exhibited higher prevalence of CVD risk factors, such as obesity, hypertension, diabetes mellitus and hypercholesterolaemia (all P < 0.001). Low SES groups also showed less adherence to the Mediterranean diet than high SES groups (MDS: 23.6 (sd 8.1) v. 25.6 (sd 5.6), P < 0.001). Higher SES index was associated with lower likelihood of having hypercholesterolaemia (OR = 0.91; 95 % CI 0.83, 1.00) and diabetes (OR = 0.83; 95 % CI 0.72, 0.95), after adjusting for various potential confounders. However, the previously mentioned inverse relationship observed between SES and prevalence of CVD risk factors was mainly explained by the dietary habits of the participants.Low SES groups showed less adherence to the Mediterranean diet compared with high SES groups. This finding may, in part, explain the higher CVD risk factors profile observed among low SES participants.