This prospective open-label randomized trial of chronic hepatitis C genotype-1b patients compared compared the efficacy and safety of peg-interferon alfa-2b administered once-weekly versus interferon alfa-2b thrice-weekly or daily, both in combination with ribavirin. Seventy-eight previously untreated patients, with biopsy-documented genotype 1 chronic HCV and persistently elevated ALT levels and detectable HCV RNA, were randomized (26 subjects each) to receive: interferon alfa-2b at 6MIUs.c./three-times-weekly (group A) or interferon alfa-2b, 3MIUs.c./daily (group B) or peg-interferon alfa-2b 1.5mcg/Kg s.c./once-weekly (group C). All regimens included standard weight-based doses of ribavirin (800, 1,000 or 1,200 mg/day) administered for 52-weeks. Patients in the three groups were comparable for age, sex, viral load, ALT value and histological-activity-index (HAI). Therapy was completed by 22, 20 and 23 patients in groups A, B and C, respectively. At the end of treatment, a complete (biochemical and virological) response was observed in 50.0% patients of group A, 57.7% of group B and 65.4% of group C. After an additional 24-weeks of follow-up, a sustained response was observed in 26.9%, 46.1% and 50.0% of patients in groups A, B or C, respectively. Therapy was discontinued by 4, 6 and 2 patients because of adverse events in the above three groups. In naive patients with chronic genotype-lb hepatitis C, a 48 week therapy with peg-interferon or interferon at daily doses combined with ribavirin were both more effective than treatment with thrice-weekly interferon in inducing end of treatment and sustained response. Peg-interferon treatment was better tolerated and provoked significantly fewer therapy discontinuations.