Metabolic Syndrome (MS) is a complex disorder including several factors predisposing to development of cardiovascular diseases and diabetes. Despite the importance of MS for the health system, the epidemiological characteristics of this condition in the Brazilian population are still scarce. The prevalence of MS as a function of gender, age and socioeconomic level was determined in a population-based study in Vitória, ES, Brazil, by using the NCEP-ATPIII diagnosis criteria. Socioeconomic, biochemical, anthropometric, and hemodynamic data were obtained in 1,663 individuals from a random sample of Vitória population (25-64 y). The estimated prevalence of MS was 29,8% (CI95 = 28-32%). No significant sex-related differences were observed. Prevalence increased from the youngest (26-34 y) to the oldest (55-64 y) group (15.8% and 48.3%, respectively). A progressive increase of MS frequency was observed in women from the higher to the lowest socioeconomic level. The most frequent trait of MS in males was high blood pressure, followed by hypertriglyceridemia, low HDL-c levels, hyperglycemia, and central obesity. In females, hypertension was also the most frequent factor, followed by low HDL-c levels, abdominal obesity, hypertriglyceridemia and hyperglycemia. Our data show that prevalence of MS is high in the studied population, even in the youngest group. Moreover, high blood pressure gives a significant contribution to the diagnosis of this syndrome in both sexes. The precocious control of risk factors is necessary to reduce the impact of cardiovascular morbidity and mortality.