This randomized, open-label, multi-center study will evaluate the sustained virological response, pharmacokinetics and safety of various combinations of danoprevir/ritonavir with Copegus plus RO5024048 and/or Pegasys in patients with chronic hepatitis C infection. Patients will be divided into 2 separate cohorts. Cohort A, previous partial responders, will be randomized to Groups 1-3 and cohort B, previous null responders, will be randomized to Groups 4-6. Patients in all groups will receive danoprevir 100 mg twice a day and ritonavir 100 mg twice a day for 24 weeks. In addition, Groups 1 and 4 will receive RO5024048 1000 mg twice a day and Copegus 1000 mg or 1200 mg twice a day for 24 weeks; Group 2 will receive Pegasys 180 microgram subcutaneously once weekly and Copegus 1000 mg or 1200 mg twice a day for 24 weeks; Groups 3, 5 and 6 will receive RO5024048 1000 mg twice a day, Pegasys 180 microgram subcutaneously once weekly and Copegus 1000 mg or 1200 mg twice a day for 24 weeks. In addition, patients in Group 6 will receive another 24 weeks of Pegasys plus Copegus treatment.

Inclusion Criteria:

• Adult patients, age 18 years and older
• Presence of hepatitis C infection, genotype 1a or 1b
• Documentation of previous treatment failure after receiving approved doses of peginterferon plus ribavirin for at least 12 weeks
• Patients must have discontinued prior hepatitis C treatment at least 12 weeks prior to study start

Exclusion Criteria:

• Infection with any hepatitis C genotype or subtype other than genotype 1a or 1b
• Patients with cirrhosis
• Patients who were discontinued from previous peginterferon plus ribavirin therapy due to reasons other than insufficient therapeutic response
• Co-infection with hepatitis B or human immunodeficiency virus (HIV)
• History or evidence of chronic liver disease other than hepatitis C