To assess the prevalence of metabolic syndrome (MS) and cardiovascular risk factors in patients with established cardiovascular disease (CVD).Epidemiologic, cross-sectional, multicentre and national study. 1,342 evaluable patients were recruited by 95 physicians of primary care, cardiology, endocrinology and internal medicine. All patients had confirmed diagnosis of CVD (myocardial infarction, coronary disease, ischaemic cerebrovascular disease and/or peripheral vascular disease) and analytical data for the study of MS according to Adult Treatment Panel-III (MS identified as presence of at least 3 components: abdominal obesity, triglyceridesor = 150 mg/dl, high density lipoproteins-cholesterol40 mg/dl in men and50 mg/dl in women, blood pressure130/85 mmHg and fasting glucose110 mg/dl).37% (n = 497) of patients presented MS, with a higher prevalence among women (51.5% versus 31.8%) (chi2 test, p0.0001). 58% of patients had abdominal obesity, 50.4% hyperglycemia, 39.7% hypertriglyceridemia, 34.4% low values of high density lipoproteins-cholesterol and 28% high blood pressure. Abdominal obesity (86.7%) and hyperglycemia (82.7%) were the most prevalent components among patients with MS. Previous ischaemic cerebrovascular disease was more prevalent among patients with MS (22.3% versus 17.5%) (chi2 test, p0.05), as well as family history of hypertension, diabetes, ischaemic cardiopathy and ischaemic cerebrovascular disease (49.1%, 46.3%, 41.1% and 27.5%) (chi2 test, p0.05). Patients with MS showed a higher probability of suffering cardiac event in the next 10 years (25.3% vs. 17.4%).The prevalence of MS among Spanish population with CVD is high, specially among women.