OBJECTIVE: To evaluate the prevalence of Hepatitis A virus (HAV) in children and adolescents with chronic liver disease in a unit of pediatric hepatology. METHODS: Between May 1999 and February 2001, we studied the prevalence of anti-HAV in 60 children and adolescents with chronic liver disease, aged between 1 and 16 years, from the Unit of Pediatric Hepatology of the Hospital de Clínicas de Porto Alegre. The total anti-HAV was determined by a commercially available competitive ELISA method (Abbott), and compared with age, sex, race, etiologic diagnosis and family income of each patient. RESULTS: A one-year old child was not included in the study because she presented twice with undetermined anti-HAV results. Among the other 59 patients, 14 (24%) presented a positive result of total anti-HAV. The ages of test-positive subjects varied between 1 and 16 years old (mean=7.7 years, median=8.5). The differences between positive and negative groups in relation to age, sex and race were not statistically significant. Family income was lower in anti-HAV positive patients, but this difference was not significant. The differences between the etiologies of liver diseases were probably more related to the age than to the etiologies of the diseases. CONCLUSIONS: In the studied population, the majority (76%) of children and adolescents with chronic liver disease are susceptible to hepatitis A virus infection and, consequently, they could present a more severe disease or even fulminant hepatitis A. We strongly suggest that these subjects receive Hepatitis A inactivated vaccine.