The purposes of this study are:

1. To test if 36 weeks of standard dose of ribavirin with PEGASYS® is non-inferior to standard dose of 48 weeks of ribavirin with PEGASYS® in SVR for patients with RVR and HVL
2. To test if the 72 weeks of treatment with PEGASYS® plus standard dose ribavirin is superior to 48 weeks of the same treatment for patients with HCV RNA seropositivity at week 12

The aims of the present study are:

1. To evaluate the efficacy and safety of 36-week versus 48-week regimen of PEGASYS® (peginterferon alfa-2a, PegIFN) plus standard-dose of ribavirin (RBV) in hepatitis C virus (HCV) genotype 1 infected, treatment-naïve CHC patients who have high viral loads (HVL, defined as baseline HCV RNA ≧ 400,000 IU/mL) and achieve a rapid virologic response (RVR) (defined as seronegativity of HCV RNA at week 4 of treatment)
2. To evaluate the efficacy and safety of 48-week versus 72-week regimen of PegIFN plus standard-dose of RBV in HCV virus genotype 1 infected, treatment-naïve CHC patients with PCR-seropositive of HCV RNA at week 12

Inclusion Criteria:

• Male and female patients *18 years of age
• Patients have never been treated with traditional interferon plus ribavirin or peginterferon plus ribavirin
• Serologic evidence of chronic hepatitis C infection by an anti-HCV antibody test
• Detectable serum HCV-RNA and HCV viral genotype 1
• Liver biopsy findings consistent with the diagnosis of chronic hepatitis C infection with or without compensated cirrhosis (Exception: hemophiliacs in whom biopsy is medically contra-indicated do not require biopsy.)
• Compensated liver disease (Child-Pugh Grade A clinical classification)
• Negative urine or blood pregnancy test (for women of childbearing potential) documented within the 24-hour period prior to the first dose of study drug
• All fertile males and females receiving ribavirin must be using two forms of effective contraception during treatment and during the 6 months after treatment end

Exclusion Criteria:

• Women with ongoing pregnancy or breast feeding
• Therapy with any systemic anti-neoplastic or immunomodulatory treatment (including supraphysiologic doses of steroids and radiation) *6 months prior to the first dose of study drug
• Any investigational drug *6 weeks prior to the first dose of study drug
• Co-infection with active hepatitis A, hepatitis B and/or human immunodeficiency virus (HIV)
• History or other evidence of a medical condition associated with chronic liver disease other than HCV (e.g., hemochromatosis, autoimmune hepatitis, metabolic liver disease, alcoholic liver disease, toxin exposures)
• Signs or symptoms of hepatocellular carcinoma
• History or other evidence of bleeding from esophageal varices or other conditions consistent with decompensated liver disease
• Neutrophil count <1500 cells/mm3 or platelet count <90,000 cells/mm3 at screening