This non-randomized, multi-center, open-label study will evaluate the pharmacokinetics and the safety and tolerability of danoprevir (RO5190591) and ritonavir in healthy volunteers and patients with mild, moderate or severe hepatic impairment. Participants will be administered repeated daily doses of danoprevir and ritonavir. The anticipated time on study treatment is 10 days.

Inclusion Criteria:

Healthy Volunteers:

• Adult healthy volunteers, 18-70 years of age
• Weight >/=50.0 kg
• Body Mass Index (BMI) 18.0-40.0 kg/m2
• Ability and willingness to abstain from alcohol-containing beverages or food from 48 hours prior to entry in the clinical study center until discharge
• Ability and willingness to abstain from grapefruit or grapefruit juice, star fruit, and Seville oranges from 7 days prior to entry in the clinical study center until discharge
• Medical history without major recent or ongoing pathology

Patients with hepatic impairment:

• Adult patients, 18-70 years of age
• Weight >/=50.0 kg
• Body Mass Index (BMI) 18.0-40.0 kg/m2
• Ability and willingness to abstain from alcohol-containing beverages or food from 48 hours prior to entry in the clinical study center until discharge
• Ability and willingness to abstain from grapefruit or grapefruit juice, star fruit, and Seville oranges from 7 days prior to entry in the clinical study center until discharge
• Stable, mild, moderate, or severe liver disease of cryptogenic, post-hepatic, hepatitis B or alcoholic origin

Exclusion Criteria:

Healthy Volunteers:

• Pregnant or lactating women and male partners of women who are pregnant or lactating
• Uncontrolled treated/untreated hypertension (systolic blood pressure >/=160 mmHg and /or diastolic blood pressure >/=105 mmHg
• Any history of clinically significant cardiovascular or cerebrovascular disease
• Creatinine clearance </=60 mL/min
• Positive test results for drugs or alcohol
• Donation or loss of blood over 450 ml within 60 days prior to screening

Patients with hepatic impairment:

• Pregnant or lactating women and male partners of women who are pregnant or lactating
• Uncontrolled treated/untreated hypertension (systolic blood pressure >/=160 mmHg and /or diastolic blood pressure >/=105 mmHg
• Any history of clinically significant cardiovascular or cerebrovascular disease
• Severe ascites at screening or admission to the clinic
• History of or current severe hepatic encephalopathy (grade 3 or higher)
• Any evidence of progressive liver disease within the last 4 weeks
• History of liver transplantation
• Creatinine clearance \