Adiponectin possesses anti-inflammatory, insulin-sensitizing and anti-atherosclerotic properties. The aim of this study was to assess the levels of serum adiponectin in patients with chronic viral hepatitis C and B and correlate them with parameters exploring insulin resistance and indices of chronic liver disease. Seventy-two patients with chronic hepatitis C virus (HCV) infection and 73 patients with chronic hepatitis B virus (HBV) infection, matched for age and sex, were studied. All individuals were examined for serum concentrations of adiponectin, insulin, C-peptide and homeostasis model assessment for insulin resistance (HOMA-IR). Viral parameters and liver histology were also evaluated. Serum adiponectin levels were significantly higher in HCV compared with HBV-infected patients. Correlation analysis in the whole group demonstrated that serum adiponectin was positively correlated with aspartate aminotransferase, alkaline phosphatase, globulins, high-density lipoprotein cholesterol and staging score, while it was negatively correlated with body mass index, insulin, C-peptide and HOMA-IR. Logistic regression analysis identified type of infection (HCV vs HBV), alcohol consumption more than 25 g daily, serum total globulin and low C-peptide as significant predictive variables associated with high adiponectin levels. Higher levels of serum adiponectin in HCV compared with HBV patients could have a role in the slower disease progression of chronic HCV infection. In addition, alcohol intake more than 25 g daily seems to be a significant predictor for hyperadiponectinaemia in patients with chronic viral hepatitis C or B. Finally, in this study, a clear positive association between adiponectin and hepatic necroinflammation or staging score was not found.