['To compare the expression of the metabolic syndrome in Spain and San Antonio, TX, two populations with major differences regarding their cardiovascular risk profile.', 'Cross-sectional analysis of population-based, epidemiological surveys using the metabolic syndrome definition of the National Cholesterol Education Program. In San Antonio, we limited our analysis to non-Hispanic whites because non-Hispanic whites are largely of European ancestry (n = 1339 in San Antonio and 2947 in Spain)', 'In men, increased central adiposity was more prevalent in San Antonio than in Spain (29.7 vs. 23.0%, p < 0.0001); in women, it was less prevalent in San Antonio than in Spain (40.2 vs. 66.4%, p < 0.0001). The metabolic syndrome followed that same pattern: more prevalent in men (28.9 vs. 20.8%, p = 0.019) and less in women from San Antonio (27.1 vs. 30.9%, p < 0.0001). In subjects with the metabolic syndrome, most women had increased central adiposity (92.6% in San Antonio and 97.5% in Spain), and most men had either increased central adiposity or blood pressure (99.2% in San Antonio and 95.0% in Spain).'] Does central adiposity determine prevalence differences of the metabolic syndrome?