Hepatitis C virus (HCV) affects approximately 4 million people in the United States, 200 million worldwide, and numbers are increasing. This viral infection can cause cirrhosis, the destruction of healthy liver cells, which are replaced by fibrous tissue over many years. HCV infection is the most common reason for liver transplantation and causes 10,000 to 20,000 deaths each year in the United States. Because the symptoms of liver damage can take so long to become apparent, all HCV-infected patients should undergo an assessment for liver fibrosis to aid in initiating and guiding antiviral therapy. The standard of care for this assessment is a liver biopsy; however, this procedure is painful, there can be significant complications, and a biopsy may give an inaccurate diagnosis in as many as 20% of patients.