Background: Highly Active Antiretroviral Therapy (HAART) has changed the clinical picture of HIV infection by reducing morbidity and mortality rates in the population. However, alterations in lipid metabolism leading to hypertriglyceridemia, hypercholesterolemia, insulin resistance, hyperglycemia and redistribution of body fat, which are risk factors for cardiovascular diseases, have emerged. Metabolic Syndrome (MS) is a complex disorder represented by a set of cardiovascular risk factors commonly associated with central adiposity and insulin resistance. Aim: Current paper evaluates the prevalence of MS in patients with HIV/AIDS using HAART from a reference Center in southern Brazil. Methods: Samples comprised patients who had the infection for at least five years and were undergoing antiretroviral therapy. Metabolic syndrome was identified according to the National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (NCEP-ATPIII). A physical examination was performed by evaluating percentage of body fat by bio-impedance and measuring blood pressure, determination of Body Mass Index and Waist-Hip Ratio, glycaemia, total cholesterol, HDL cholesterol, LDL cholesterol and triglycerides. Results: 184 patients were evaluated. MS prevalence was 30% (55 patients), with 30 (16.3%) males and 25 (13.7%) females. Conclusions: Brazil was among the first country profoundly impacted by the HIV/AIDS epidemic but today, Brazil has less than 1% adult HIV prevalence, implemented treatment and prevention programs early in the epidemic. Whereas there is currently a significant increase in the survival of HIV patients by HAART, the patients reveal a higher prevalence of Metabolic Syndrome in this specific population requiring political strategy of care to this population.