Treatment of chronic hepatitis C in renal-transplant (RT) recipients with alpha-interferon is associated with a high rate of acute rejection. We therefore evaluated the biochemical, virological, histological efficacies, as well as the safety of one year ribavirin monotherapy in 16 HCV-(+) RNA (+) RT patients (group A) matched to 32 HCV-(+) RNA (+) RT patients (group B) who did not receive ribavirin. Ribavirin was initially started at a daily dose of 1000 mg and then adapted to hemoglobin level. Ribavirin monotherapy was associated with a significant decrease in AST, ALT and gamma glutamyl transpeptidase levels. Serum creatinine decreased as well. When proteinuria was present (n = 5), this decreased or disappeared. There was no significant changes in HCV viremia. The histological analysis of liver biopsies revealed a significant progression in liver fibrosis with no improvement in inflammation scores. There was a significant decrease in hemoglobin levels, despite an important support by recombinant erythropoeitin. However, in three cases, ribavirin therapy had to be stopped. In group B, after 1 year of follow up, there was a significant increase in serum ALT and creatinine values. Proteinuria decreased in only 2 of 12 patients. In conclusion, one year ribavirin therapy in HCV-(+) RNA (+)ve RT has no impact upon liver histology, although it improves liver enzyme levels. It impact upon renal function remains unknown. Nevertheless when proteinuria is present it disappears.