The benefit of the triple therapy (interferon + amantadine + ribavirim) is still unknown. The efficacy of induction doses of interferon-alpha-2a monotherapy or in combination with ribavirin and/or amantadine was evaluated in interferon non-responders with chronic hepatitis C. A total of 378 patients were randomized. All the groups received the same doses and duration of interferon-alpha-2a: (i) interferon 9 MUI/day for 4 weeks and then 3 MUI/3 t.i.w. for 44 weeks (n = 53); (ii) interferon in combination with amantadine 100 mg twice daily for 48 weeks (n = 111); (iii) interferon in combination with ribavirin 1000-1200 mg (n = 106); (iv) interferon in combination with amantadine and ribavirin (n = 108). Baseline parameters were similar in the four groups. Sustained virological and biochemical responses were 13%, 6%, 18% and 22% respectively. No significant differences were found between double ribavirin arm vs triple therapy, but the difference was significant between interferon-amantadine (P = 0.008) and triple therapy (P = 0.0005). Hence, the induction doses of interferon in combination with ribavirin or ribavirin plus amantadine showed encouraging results in patients with chronic hepatitis C who were resistant to interferon. However, triple therapy is not superior to double.