The pathogenetic mechanisms for liver damage in acute hepatitis C are not clear, but a host immune cellular response may be involved. In chronic hepatitis C, there is strong evidence that host cellular immune response is involved in the control of viral replication and contributes to hepatocellular damage. As hepatitis C virus infection persists, continuous liver damage and regeneration, together with enhanced fibrogenesis, may eventually lead to cirrhosis in a proportion of patients. Transplant patients on high-dose immunosuppression may have high-level intrahepatic hepatitis C viral expression, and, in this setting, the virus may induce direct cytopathic liver damage.