Hepatitis C is a common cause of chronic liver disease that may progress to cirrhosis. We conducted a multicenter double-blind placebo-controlled trial of ribavirin 600 mg given orally twice daily for 36 weeks with follow-up off therapy for an additional 16 weeks. Fifty-nine patients with compensated chronic hepatitis C were entered. Efficacy was measured at the end of therapy and after follow-up by normalization of alanine aminotransferase (ALT), improvement in liver histology, reduction in hepatitis C virus (HCV) RNA level and improvement of symptoms. Among the ribavirin recipients, 12 of 29 (41.4%) had normal ALT values at 36 weeks compared with only 1 of 30 (3.3%) placebo recipients (P < .001). No patient maintained a normal ALT when therapy was stopped. No significant decrease in level of HCV RNA was observed during the study. Histological improvement among subjects who normalized ALT (-1.67 Knodell index) was significantly greater than that in other treated patients (+0.33 Knodell index; P < .05). Fatigue improved in 19.2% of ribavirin-treated subjects and in 8.3% of placebo recipients whereas no worsening of fatigue was reported by ribavirin recipients compared with 16.7% of controls. This difference in fatigue was significant at weeks 36 and 52 (P < .05; .02, respectively). Adverse events were generally comparable between treatment groups except for a reversible hemolytic anemia experienced by ribavirin recipients. Chest pain was noted in four patients on ribavirin. Ribavirin was well tolerated and improved aminotransferase values and reduced fatigue in patients with hepatitis C viral infection while treatment was being administered. Because this action was produced without change in viral level, the mechanism of action of this agent requires further investigation.