Background. Patients with chronic hepatitis C infected by hepatitis A virus have a substantial risk of fulminant hepatitis or death, while the course of hepatitis A virus is uncomplicated in most subjects with chronic hepatitis B. Aim. To evaluate the prevalence of anti-hepatitis A virus antibodies and the incidence of hepatitis A virus seroconversion in a nationwide sample of 530 patients with chronic hepatitis B and/or hepatitis C infection initially susceptible to this infection after a follow-up of some years. Results. The overall anti-hepatitis A virus prevalence was 85.7%, with no difference between males and females. By the age of 50 years, almost all patients were found to have been exposed to hepatitis A virus. After a mean follow-up period of 76 months the overall anti-hepatitis A virus seroconversion rate in the 76 initially susceptible individuals was 1.2 per 100 person/years. However, it was 0.3 per 100 person/years in those hepatitis B surface antigen positive but 3.36 per 100 person/years in those anti-hepatitis C virus positive. None of the seroconverters was affected by a clinically evident disease or showed deterioration of underlying chronic liver disease. Conclusions. The present study shows that Italian patients > 50 years of age with chronic liver disease have already been exposed to hepatitis A virus suggesting that anti-hepatitis A virus screening is not advisable in these subjects.