['The prevalence of metabolic syndrome and its possible impact on the severity of liver histological lesions have not been studied prospectively in chronic liver diseases.', 'To investigate the prevalence of metabolic syndrome in patients with chronic viral hepatitis or non-alcoholic steatohepatitis, and to determine its associations with histological severity.', "We prospectively included 317 patients (hepatitis B e antigen-negative chronic hepatitis B: 95, chronic hepatitis C: 176, non-alcoholic steatohepatitis: 46) with liver biopsy. Metabolic syndrome was defined using the Adult Treatment Panel III criteria. Histological lesions were evaluated according to Ishak's or Brunt's classification.", 'Metabolic syndrome was present in 10.4% of patients being significantly more prevalent in non-alcoholic steatohepatitis than in chronic viral hepatitis (41.3% vs. 5.1%, P < 0.001). In chronic viral hepatitis, cirrhosis (stages 5-6) was independently associated with increasing age, higher aspartate aminotransferase and gamma-glutamyl-transpeptidase levels, severe necroinflammation and metabolic syndrome (P = 0.016). In non-alcoholic steatohepatitis, severe fibrosis (stages 3-4) was independently associated with severe necroinflammation and metabolic syndrome (P = 0.033). Presence of metabolic syndrome was not associated with presence or severity of steatosis both in chronic viral hepatitis and in non-alcoholic steatohepatitis.'] Is metabolic syndrome associated with severe fibrosis in chronic viral hepatitis and non-alcoholic steatohepatitis?