In order to assess the prevalence, causes, and severity of chronic liver dysfunction (LD) in heart transplant patients, 80 transplanted patients followed for 60 months (median; range, 1.5-98 months) were reviewed. Sustained liver dysfunction was found in 50 patients, occurring during the first year after heart transplantation in 42 (84%) of them. Most patients were asymptomatic (80%). Causes for the liver dysfunction included non-A, non-B hepatitis in 16 cases (32%), viral B hepatitis in 13 (26%), delta hepatitis in one (2%), drug-induced hepatitis in six (12%), and cardiac failure in seven (14%). Anti-HCV antibodies were found in 56.2% of patients with non-A, non-B hepatitis and in 22% of patients with HBV hepatitis. It was found neither in patients with drug-induced hepatitis cardiac failure nor in patients with normal liver tests. This study outlines a high prevalence of LD (62.5%) in heart transplant patients, the high frequency of viral-related chronic LD (usually of moderate severity), and high incidence of HCV and HBV hepatitis.