The purpose of the study is to determine the safety, pharmacokinetics and efficacy of orally administered VX-135 with ribavirin in treatment naive subjects with chronic hepatitis C infection.

Up to twenty (20) subjects with CHC GT1 infection will be randomized in a 1:1 ratio (with stratification by IL-28B genotype (CC versus non-CC)) to evaluate VX-135 low dose or high dose both given in combination with RBV for 12 weeks.

Safety and tolerability will be evaluated on an ongoing basis through assessment of adverse events (AEs), lab evaluations and physical examinations. Subjects will be monitored from Day 1 through end of follow-up for virologic breakthrough or relapse.

Key Inclusion Criteria:

• Subjects (male and female) must be between 18-60 years of age
• Subjects must have Chronic Hepatitis C
• Subjects must be treatment naive
• Subjects must have laboratory values at screening within limits as specified by the protocol

Key Exclusion Criteria:

• Evidence of cirrhosis
• Female subjects who are pregnant or nursing or male subjects with a female partner of childbearing potential who is unwilling to adhere to the contraception requirements, is pregnant or nursing, or planning to become pregnant during the study
• any other cause of significant liver disease in addition to hepatitis C
• Diagnosis of or suspected hepatocellular carcinoma