This is a single arm, open-label study which will be opened at specific clinical sites at the request of an investigator for the treatment of individual subjects for whom there are no other treatment options. Subjects will be treated for 24 weeks with sofosbuvir (400mg QD) with RBV; pegylated interferon may be added at the discretion of the investigator.

Inclusion Criteria:

• Age > or = 18 years
• Previously undergone orthotopic liver transplant (OLT) at least 2 months prior to the planned start of dosing
• Aggressive Hepatitis C infection (including fibrosing cholestatic hepatitis C)
• Life expectancy of < 12 months if the HCV is left untreated

Exclusion Criteria:

• History of clinically significant drug allergy to nucleoside/nucleotide analogs
• Participation in a clinical study with an investigational drug or biologic within 1 month prior to anticipated dose administration, unless information is available to determine that there is no safety or drug-drug interaction risk to the subject
• Unable or unwilling to follow the contraception requirements