The aim of the study was to evaluate the efficacy of triple antiviral therapy with interferon, ribavirin, and amantadine in comparison with interferon and ribavirin combination treatment in patients with interferon-nonresponsive chronic hepatitis C. We performed an open-label, prospective randomized controlled trial at a secondary referral center. We used a 2:1 ratio, patients received interferon, ribavirin, and amantadine, or interferon and ribavirin for 12 months, and were followed up for an additional 6 months. Ninety-four consecutive adult interferon nonresponders with chronic hepatitis C were screened. Sixty consecutive elected patients entered the study. No patients withdrew because of adverse effects. Forty patients received interferon alfa (5 megaunits on alternate days), ribavirin (800-1,000 mg daily), and amantadine (200 mg daily) for 12 months, and 20 patients received the same treatment without amantadine. At the end of follow-up, alanine transaminase (ALT) level normalization was maintained in 23 of 40 patients (57%) after triple therapy, but in 2 of 20 patients (10%) after double therapy (P <.001, RR = 2.11, 95% CI, 1.43-3.12), whereas disappearance of serum HCV RNA persisted in 19 of 40 patients (48%) and in 1 of 20 patients (5%), respectively (P <.001, RR = 1.81, 95% CI, 1.32-2.47). The safety profile was similar in the 2 groups. In conclusion, in patients with interferon-nonresponsive chronic hepatitis C, triple antiviral therapy for 1 year results in a high rate of sustained biochemical and virologic responses.