OBJECTIVE We performed a randomized trial on pegylated interferon alfa-2a (Peg-IFNalpha) monotherapy vs Peg-IFNalpha and ribavirin in non-cirrhotic liver transplant recipients with recurrent hepatitis C. METHODS Forty-two patients transplanted for HCV-related cirrhosis 12-96 months earlier were randomized to Peg-IFNalpha monotherapy (180 microg weekly) or Peg-IFNalpha and ribavirin, up to the maximum tolerated dose, for 48 weeks. RESULTS Early virological response (EVR, i.e., HCV-RNA2 log drop at week 12) occurred in 76% of the monotherapy and 71% of the combination groups, respectively (intention-to treat). Sustained virological response (SVR) occurred in 8 (38%) and 7 (33%) patients, respectively. EVR had a positive predictive value for SVR of 50% and 47%, respectively, and a 100% negative predictive value in both groups. Six drop-outs occurred in the monotherapy (including 3 rejections) and 7 in the combination groups (including one rejection). Peg-INFalpha dose was reduced in 7 and 8 patients, respectively. The average daily dose of ribavirin was 435 mg/day. CONCLUSIONS Peg-IFNalpha-2a, with or without ribavirin, induces SVR in one-third of transplant recipients with recurrent hepatitis C. Treatment cessation is indicated in patients without EVR. The low SVR rate is mainly due to inability to sustain full doses of antivirals and lack of the booster effect of ribavirin.