Background& Aims: Standard therapy of patients with chronic hepatitis C virus (HCV) infected with HCV genotype-2 or -3 is the combination of pegylated interferon-α and ribavirin for 24 weeks. Whether shorter treatment durations are possible for these patients without compromising sustained virologic response rates is unknown. Methods: Patients chronically infected with HCV-2 (n = 39), HCV-2/3 (n = 1), or HCV-3 (n = 113) were treated with peginterferon-α -2a (180 μ g/wk) plus ribavirin 800- 1200 mg/day. HCV RNA was quantitatively assessed after 4 weeks. Patients with a rapid virologic response (HCV RNA below 600 IU/mL) were randomized for a total treatment duration of 16 (group A) or 24 weeks (group B). All patientswith HCV RNA ≥ 600 IU/mL at week 4 (groupC) were treated for 24 weeks. End-of-treatment and sustained virologic response were assessed by qualitative RT-PCR (sensitivity 50 IU/mL). Results: Only 11 of 153 patients (7% ) were allocated to group C. End-of-treatment and sustained virologic response rates were 94% and 82% , (group A), 85% and 80% (group B), and 73% and 36% (group C), respectively. In patients infected with genotype HCV-3 and high viral load (>800,000 IU/mL), a significant lower sustained virologic response rate was found than in patients infected with HCV-3 and a viral load lower or equal to 800,000 IU/mL (59% vs 85% , respectively; P = .003). Conclusions: In HCV-2 and -3 (low viral load)-infected patients who have a rapid virologic response, treatment for 16 weeks with peginterferon-α -2a and ribavirin is sufficient. In patients infected by HCV-3 (high viral load), longer treatment may be necessary. Background & Aims: Standard therapy of patients with chronic hepatitis C virus (HCV) infected with HCV genotype-2 or -3 is the combination of pegylated interferon-α and ribavirin for 24 weeks. Whether shorter treatment durations are possible for these patients without pacification sustained Methods: Patients chronically infected with HCV-2 (n = 39), HCV-2/3 (n = 1), or HCV-3 (n = 113) were treated with peginterferon-α-2a 180 μg / wk) plus ribavirin 800-1200 mg / day. HCV RNA was quantitatively assessed after 4 weeks. Patients with a rapid virologic response (HCV RNA below 600 IU / mL) were randomized for a total treatment duration of 16 (group All patients with HCV RNA ≥ 600 IU / mL at week 4 (group C) were treated for 24 weeks. End-of-treatment and sustained virologic response were assessed by qualitative RT-PCR (sensitivity 50 IU / mL) Results: Only 11 of 153 patients (7%) were allocated to group C. End-of-treatment and sus In patients infected with genotype HCV-3 and high viral (group A), 85% and 80% (group B), and 73% and 36% (group C) a significant lower sustained virologic response rate was found in patients infected with HCV-3 and a viral load lower or equal to 800,000 IU / mL (59% vs 85%, respectively; P =. 003). Conclusions: In HCV-2 and -3 (low viral load) -infected patients who have a rapid virologic response, treatment for 16 weeks with peginterferon-alpha-2a and ribavirin is sufficient. high viral load), longer treatment may be necessary.