Individuals with the metabolic syndrome (MS) are at high risk for coronary heart disease and may benefit from aggressive lifestyle modification. In this study, we evaluated the effect of leisure time physical activity (PA) and the Mediterranean diet (MD) on the prevalence of the MS.The ATTICA study is a health and nutritional survey. On the basis of a multistage, random sampling, 1128 men and 1154 women (>18 years old) without any evidence of cardiovascular disease or diabetes mellitus were enrolled from the greater Athens area during 2001 to 2002. The MS was defined according to the National Cholesterol Education Program (NCEP) Adult Treatment Panel (ATP) III criteria. PA was determined from a detailed questionnaire and graded according to the kcal/min expanded. MD was assessed through a validated nutrient questionnaire.The overall prevalence of the MS was 453 of 2282 subjects (19.8%). Of these subjects, 284 (25.2%) were men and 169 (14.6%) were women (P <.001). The prevalence of the MS increased accordingly to age (P for trend <.001). With multiple logistic regression analysis, the odds ratio of having the MS when the participant consumed the MD was 0.81 (95% CI, 0.68-0.976), and when even a little to moderate PA (<7 kcal/min)was reported, the odds ratio was 0.75 (95% CI, 0.65-0.86). The higher levels of inflammation and coagulation markers among participants with MS did not explain much of the aforementioned effect of lifestyle modification.MS is common in Greece and is becoming even more common in the middle-aged population. The suggested therapeutic lifestyle approach may contribute to the reduction of the prevalence of the MS, beyond the levels of several lipid, inflammation, and coagulation markers.