Background. Carbohydrate 19.9 antigen (CA19.9) has been used in the diagnosis and followup of gastrointestinal tumours. The aim of this prospective longitudinal study was the evaluation of CA19.9 levels in patients with chronic hepatitis and hepatic cirrhosis hepatitis C virus and B virus correlated. Materials and Methods. 180 patients were enrolled, 116 with HCV-related chronic liver disease (48% chronic hepatitis, 52% cirrhosis) and 64 with HBV-related chronic liver disease (86% chronic hepatitis, 14% cirrhosis). Patients with high levels of CA19.9 underwent abdominal ecography, gastroendoscopy, colonoscopy, and abdominal CT scan. Results. 51.7% of patients with HCV-related chronic liver disease and 48.4% of those with HBV-related chronic liver disease presented high levels of CA19.9. None was affected by pancreatic or intestinal neoplasia, cholestatic jaundice, or other diseases potentially able to induce Ca19.9 elevations. CA19.9 levels were elevated in 43.3% of HCV chronic hepatitis, in 56.3% of HCV cirrhosis, in 45.1% of HBV chronic hepatitis, and in 58% of HBV cirrhosis. Conclusions. CA19.9 commonly increases in the serum of patients with chronic viral hepatitis. Elevation of CA 19.9 is not specific for neoplastic disease and is related to the severity of fibrosis and to the viral aetiology of hepatitis.