Background and aim: Since little information on the metabolic syndrome (MS) is available in Latin America, the aim of this study was to explore whether and to what extent differing socioeconomic conditions influence the prevalence of MS and its associated factors among young adults from two towns in Latin America: semi-rural Limache (L), Chile, and urban Ribeirão Preto (RP), Brazil. Methods and results: A cross-sectional study based on two independent investigations of 22- to 28 year-old subjects using a common methodology. The prevalence of MS (according to the US National Cholesterol Education Program) and its risk factors (smoking habit, alcohol and caloric intake, obesity, physical activity and socioeconomic conditions) were assessed. The prevalence of MS was 10% in L and in RP men, but was lower (4.8%) in RP women. Hyperglycemia was very low (0.8% in L and 1.1% in RP), while the prevalence of low HDL cholesterol levels was high (66.7% and 42.2%, respectively). Intermediate prevale