The aim of this study was to determine whether infection by the hepatitis C virus (HCV) recurs after orthotopic liver transplantation (OLT) and to define the natural history of post-transplantation chronic hepatitis due to HCV. Of 70 patients, 10 (14.3%) were found to have antibodies to HCV before transplantation. After OLT 14 of the 70 patients (20%) had positive anti-HCV antibodies: 8 of 10 positive pre-OLT (80%) and 6 of 60 negative pre-OLT (10%). Of 14 patients anti-HCV+ post-OLT (57%), developed 8 chronic hepatitis: chronic persistent hepatitis in three patients, chronic lobular hepatitis in three patients and chronic, active hepatitis in two patients. We treated four patients with interferon obtaining normalization of transaminases in three of them after 6 months, but with a severe relapse in two. These results suggest that hepatitis C recurs in a majority, of liver transplant recipients and that morbidity is an important consideration. Interferon treatment of these patients requires further study to obtain conclusive results.