This study will evaluate the safety, tolerability, and efficacy of vaniprevir when administered concomitantly with pegylated interferon (peg-IFN) and ribavirin (RBV) to treat treatment-naive genotype 1 hepatitis C virus (HCV)-infected patients.

Inclusion Criteria:

• Patient has chronic genotype 1 HCV infection
• Patient has had a liver biopsy without evidence of cirrhosis
• Patient has had an eye exam prior to the start of study
• Female patients capable of having children and male patients with female partners capable of having children agree to use two forms of birth control throughout the study

Exclusion Criteria:

• Patient has had previous treatment with: 3 or more doses IFN, peg-IFN, and/or RBV; and stopped treatment due to intolerance of one of the drugs; other antiviral or investigational therapies or vaccines for HCV
• Female patient is pregnant or breastfeeding
• Patient has chronic hepatitis not caused by HCV
• Patient has evidence of cirrhosis of the liver
• Patient has HIV
• Patient has active hepatitis B infection
• Patient has non-genotype 1 HCV infection
• Patient consumes excessive amounts of alcohol