The aim of this study was to ascertain if hyperhomocysteinemia is associated with the metabolic syndrome. The metabolic syndrome is a cluster of cardiovascular risk factors. Hyperhomocysteinemia is an obvious independent risk factor for atheroma, and thrombosis morbidity and mortality. EPIMIL is a prospective epidemiological survey, which began with a crosssectional study of cardiovascular risk factors in a French male population, followed by monitoring for 10 years. Initial data collection, blood pressure measurement, ECG, and blood samples have been performed. For the metabolic syndrome, we used the criteria of the Third Report of the National Cholesterol Education Program-Adult Treatment Panel III (NCEP ATP III) on detection, evaluation, and treatment of high blood cholesterol in adults. Out of 2045 men aged 20-58 years (37.7 +/- 8.7 years), 185 (9%) have metabolic syndrome (at least three criteria), 587 (29%) have a plasma homocysteine level of >/=12 micromol/L, and 202 (10%) have a level of >/=15 micromol/L. Mean homocysteinemia is 10.97 +/- 5.01 micromol/L for the whole population and does not differ significantly with (11.4 +/- 6 micromol/L) or without (10.9 +/- 5 micromol/L) the metabolic syndrome, as does its value distribution. Nor does it correlate with the Body Mass Index (BMI), waist and hip measurements, or blood glucose, HbA1c, insulin resistance, and cardiovascular risk markers (CRPus, microalbuminuria). It weakly correlates with systolic and diastolic blood pressure, creatinine clearance, tobacco use, cholesterolemia, triglycerides, and free fatty acids, but not with HDL and LDL fractions, or lipoprotein(a) (Lp(a)). It contributes slightly to the 10-year vascular risk according to the Framingham equations or Score system. In this male population, homocysteinemia and the prevalence of hyperhomocysteinemia do not differ with or without the metabolic syndrome. Plasma homocysteine level does not correlate with its main criteria. Hyperhomocysteinemia is not associated with the metabolic syndrome; nevertheless, it should be monitored in high-risk cardiovascular patients.