Chronic hepatitis C virus (HCV) infection remains a world-wide public health problem. Therapy with interferon plus ribavirin leads to viral clearance in about 50% of treated patients. New treatment using direct-acting antiviral agents (DAAs) has the potential to cure patients unresponsive to the interferon-based therapy. In this talk, Iwill review mathematical models used to study HCV dynamics under interferon-based therapy and introduce new models for DAAs. Treatment implications related to modeling results will be discussed.