BACKGROUND: Interferon monotherapy for chronic hepatitis C virus (HCV) infection leads to sustained viral eradication in a minority of patients. However, in selected groups of patients, sustained virological response is observed in as many as 50% of patients. High initial interferon dose (induction therapy) has been reported to increase the initial response rate. We have studied the effect of interferon induction therapy in patients infected with HCV genotype 2b/3a, low viral load and no cirrhosis. METHODS: A total of 71 treatment-naive HCV RNA-positive patients with biopsy-confirmed chronic hepatitis, with genotype 2b or 3a, viral load < or = 3 million copies per ml and no cirrhosis were randomized to receive either standard interferon therapy (3 MIU interferon-alpha-2a thrice weekly) for 26 weeks or 6 MIU interferon-alpha-2a daily for 4 weeks (induction group) followed by the standard dose (3 MIU thrice weekly) for 22 weeks. Those with persistent HCV RNA at 4 weeks stopped treatment. Patients were monitored for HCV RNA during and following treatment, and data were interpreted according to intention-to-treat analysis. RESULTS: Viral clearance occurred more rapidly (after 4 weeks) in the induction group (33/36 = 92%) compared to the standard interferon group (21/35 = 60%) (P = 0.01). Among the initial responders, 23/33 (induction group) compared to 16/21 (standard group) were persistently HCV RNA-negative at the end of treatment. At 52 weeks (6 months' follow-up), 22/36 (61%) (induction group) compared to 10/35 (29%) (standard group) were HCV RNA-negative. Among initial responders, 22/33 (induction group) and 10/21 (standard group) achieved a sustained virological response. Among end-of-treatment responders, 22/24 (induction group) and 10/16 (standard group) were HCV RNA-negative at 6 months' follow-up (P = 0.013). CONCLUSIONS: In patients infected with HCV genotype 2b/3a, low viral load and without cirrhosis, IFN induction therapy increases the initial viral clearance and reduces the risk of relapse in end-of-treatment responders. A sustained virological response was achieved in 61% of the patients receiving IFN induction therapy.