BACKGROUND & AIMS: Recurrence of hepatitis C virus (HCV) infection is a relevant problem of liver transplantation programs. We evaluated the effect of antiviral therapy on disease progression in 81 HCV-infected liver transplantation recipients. METHODS: Patients with mild hepatitis C recurrence (fibrosis stage F0 to F2, n = 54) were randomized to no treatment (group A, n = 27) or peginterferon alfa-2b/ribavirin for 48 weeks (group B, n = 27). Patients with severe recurrence (F3 to F4, cholestatic hepatitis) were treated (group C, n = 27). All patients (n = 81) underwent a liver biopsy at baseline and after follow-up; paired hepatic venous pressure gradient (HVPG) measurements were available in 51 patients. RESULTS: Thirteen (48%) patients of group B and 5 (18.5%) of group C achieved sustained virological response. Liver fibrosis progressed > or =1 stage in 40 (49%) of 81 patients: 19 (70%) of group A versus 7 (26%) of group B (P = .001) and in 14 (54%) of group C. HVPG increased (6.5 to 13 mm Hg, P < .01) in patients in whom fibrosis worsened, whereas it decreased (5 to 3.5 mm Hg, P = .017) or remained unchanged in those with fibrosis improvement or stabilization, respectively. The only variable independently associated with fibrosis improvement/stabilization was treatment (odds ratio [OR] =3.7, 95% confidence interval [CI] 1.3 to 10, P = .009). Among treated patients, alanine aminotransferase (ALT) normalization and viral clearance were independently associated with histological or hemodynamic improvement/stabilization (OR 5.3, 95% CI 1.5 to 18, P < .01; OR 7.4, 95% CI 1.4 to 38, P = .01; respectively). CONCLUSIONS: Our data demonstrate that in liver transplantation recipients, antiviral therapy slows disease progression (particularly in sustained virological responders), as shown by its effects on liver histology and on HVPG.