BACKGROUND: Chronic hepatitis C may lead to cirrhosis and hepatocellular carcinoma in a subset of patients. Because response rates with interferon alfa therapy are unsatisfactory, new therapies are needed. METHODS: We conducted a three-arm, randomized trial in 45 interferon-naive men (mean age 40.6 +/- 12 years) with chronic hepatitis C to compare treatments: group A, ribavirin alone (15 mg/kg daily for 6 months); group B, interferon alone (3 MU thrice weekly for 6 months); and group C, interferon plus ribavirin at the above doses. Histologic outcomes of therapy were assessed by pretreatment and post-treatment liver biopsies. RESULTS: In group A, alanine aminotransferase levels normalized during therapy in 66% of those with HCV-1b and 34% of those with HCV-2a, but all patients relapsed after treatment ended. In group B, alanine aminotransferase levels normalized during treatment in 66%, 75%, and 100% of patients infected with HCV-1b, HCV-2a, and HCV-3, respectively; however, a sustained response was noted in only 25% of those with HCV-3. In group C, a sustained normalization of alanine aminotransferase with negative serum HCV RNA was seen in 20% of those with HCV-1b, 40% of those with HCV-2a, and 75% of those with HCV-3 12 months after therapy. One year after therapy ended, group C demonstrated a significant sustained response (47%) as well as a significant reduction in piecemeal necrosis and portal inflammation (p