Liver transplant recipients with recurrent hepatitis C virus (HCV) infection often have histological hepatitis, and in some patients, graft failure develops. The aim of this nonrandomized study is to determine the efficacy and tolerability of interferon alfa (IFN alfa) alone and IFN alfa and ribavirin combination therapy in such patients. Forty transplant recipients with recurrent hepatitis were initiated on therapy with IFN alfa-2b at 3 million units (MU) three times weekly for 1 month followed by 5 MU three times weekly for 5 months. Twenty patients were administered IFN alfa-2b, 3 MU three times weekly for 1 month followed by 5 MU three times weekly for 11 months, and ribavirin, 600 mg, twice daily orally for 12 months concurrently. The primary end point was sustained clearance of serum HCV RNA, and secondary end points were serum alanine aminotransferase (ALT) level normalization and histological improvement. Thirty patients completed 6 months of IFN-alfa monotherapy and 15 patients completed 12 months of IFN alfa and ribavirin combination therapy. End-of-treatment biochemical responses were similar in the two groups (IFN alfa, 20% v combination therapy, 25%); however, viral clearance was greater in the combination-therapy group (40% v 15%; P = .04). Six months after the completion of therapy, only 1 patient (2.5%) in the IFN-alfa group and 4 patients (20%) in the combination-therapy group were HCV RNA negative (P = .03). Serum ALT and HCV RNA levels declined significantly in both groups during therapy. There was no improvement in inflammatory grade, and fibrosis score was worse in both groups. Ten patients (25%) in the IFN-alfa group and 5 patients (20%) in the combination-therapy group withdrew because of adverse effects. We conclude that in liver allograft recipients with recurrent hepatitis C, combination therapy with IFN alfa and ribavirin is more efficacious than treatment with IFN alfa alone. However, the efficacy is limited by tolerability.