Hepatitis C virus (HCV) infection invariably recurs after liver transplantation (LT), leading to significant morbidity and mortality. Although the combination of pegylated interferon-alpha (IFN-alpha)/ribavirin is the preferred treatment for these patients, the optimal schedule remains undetermined. In an uncontrolled trial, 19 patients with HCV infection recurring after LT received pegylated IFN-alpha(2a), 180 mug weekly, and ribavirin, 10 mg/kg body weight daily, for 48 weeks. The proportion of patients with undetectable HCV RNA in their serum after 12 weeks of treatment was 53%. Five patients (26%) dropped out of the study due to intolerance (in 2 cases), depression (in 1), or infectious complications (in 2). A sustained virological response (SVR), defined as undetectable serum HCV RNA 24 weeks after the end of treatment, was observed in 9/19 patients (47%). SVR was associated with an early virological response after 12 weeks of therapy (P<0.001) and a treatment duration >80% (P=0.02), but not with baseline HCV RNA level or a cumulative dose of pegylated IFN-alpha(2a) or ribavirin >80% of the scheduled dose. All 4 patients with genotype 2 or 3 reached SVR, as compared with 33% of patients with genotype 1 or 4 (P=0.03). A 48-week course of pegylated IFN-alpha(2a)/ribavirin therapy is effective in patients with recurrent HCV infection after LT.