HERMES is a prospective study, including all treatment-naive patients attending scheduled visits at hospitals in the CISAI group in 2007. The present cross-sectional analysis aims to assess the baseline prevalence and characteristics of Metabolic Syndrome (MS) in a population of HIV-positive treatment-naive patients. MS was diagnosed using the National Cholesterol Education Program (NCEP) definitions. A total of 292 subjects were enrolled, median age was 37 years, 75% of them were males. The prevalence of MS was 12.3%. The most frequent trio of abnormalities that led to the diagnosis of MS was high blood pressure, triglycerides and HDL. Univariate analysis showed that MS was associated with the following variables: age, education, physical activity, advanced HIV disease (CDC stage C or HIV-RNA > 100,000 copies + CD4 < 100 cells/mm3). Higher educational levels remained protectively associated with MS in multivariate analysis. A higher risk of MS was also associated with advanced HIV disease. Actually, treatment-naïve HIV-positive patients in an advanced stage of the disease have a higher prevalence of abnormal levels of triglycerides, HDL cholesterol and blood glucose than those at a less advanced stage. These findings of the HERMES study suggest, therefore, that HIV infection per se is associated to MS.