Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) ; Background: Chronic kidney disease (CKD) and metabolic syndrome are characterized by overlapping disorders, including glucose intolerance, hypertension, dyslipidemia, and, in some cases, obesity. However, there are no specific criteria for the diagnosis of metabolic syndrome in CKD. Metabolic syndrome can also be associated with increased risk of mortality. Some traditional risk factors may protect dialysis patients from mortality, known as "reverse epidemiology." Metabolic syndrome might undergo reverse epidemiology. The objectives were to detect differences in frequency and metabolic characteristics associated with three sets of diagnostic criteria for metabolic syndrome, to evaluate the accuracy of insulin resistance (IR) and inflammation to identify patients with metabolic syndrome, and to investigate the effects of metabolic syndrome by three sets of diagnostic criteria on mortality in chronic hemodialysis patients.Methods: An observational study was conducted. Diagnostic criteria for metabolic syndrome proposed by National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III), International Diabetes Federation (IDF), and Harmonizing the Metabolic Syndrome (HMetS) statement were applied to 98 hemodialysis patients.Results: The prevalence of metabolic syndrome was 51%, 66.3%, and 75.3% according to NCEP ATP III, IDF, and HMetS criteria, respectively. Diagnosis of metabolic syndrome by HMetS was simultaneously capable of revealing both inflammation and IR, whereas NCEP ATP III and IDF criteria were only able to identify IR. Mortality risk increased in the presence of metabolic syndrome regardless of the criteria used.Conclusions: The prevalence of metabolic syndrome in hemodialysis varies according to the diagnostic criteria used. IR and inflammation predict metabolic syndrome only when diagnosed by HMetS criteria. HMetS was the diagnostic criteria that can predict the highest risk of mortality.