Rapidly progressive and ultimately fatal liver failure with evolution to cirrhosis developed in a heart transplant recipient following infection by hepatitis C virus. Antiviral antibodies and the presence of viral RNA were analyzed throughout the course of the disease. After a weak initial response to a single viral epitope (c22-3), serology became negative, the infection remaining detectable by polymerase chain reaction only. This case demonstrates the potentially severe consequences of hepatitis C virus infection under immunosuppression. The incidence of this infection may be underestimated, as the presented case apparently would not have been detected if serology had been used for diagnosis. (C) Journal of Hepatology.