Fourteen patients with chronic hepatitis C who had a sustained response to a 60-week interferon alfa-2b treatment course were followed, biochemically and virologically, 2 years after treatment cessation. Biopsies were repeated in 12 of 14 for histological and virological evaluation at 2-year follow-up. All 14 patients had normal serum alanine transaminase (s-ALT) levels and were negative for hepatitis C virus (HCV) RNA in serum during treatment and at short-term follow-up 6 months post-treatment. At 2-year follow-up, 13 patients still had normal ALT levels (< 0.6 mukat/L for women; < 0.8 mukat/L for men), 1 a near normal level (0.76 mukat/L); all were HCV RNA negative in serum, and 11 of 12 also in the liver. Liver histology improved during treatment and remained stable during the 2-year follow-up. The authors conclude that most sustained responders, who have normal ALT levels and are nonviremic at short-term follow-up 6 months after interferon treatment, will continue to have a durable long-term response without relapse of the viremia.