Primary liver cancer is the sixth most common cancer in the world and the third most common cause of death attributable to cancer. Most primary liver cancers are hepatocellular carcinoma (HCC), accounting for 85% to 90% of cases. There is a trend of growing incidence of HCC in the United States. One of the most important risk factors for developing HCC is chronic hepatitis C virus (HCV) infection. Although several studies suggested the preventive effect of interferon from developing HCC in HCV-infected individuals, these findings need to be validated in large prospective and randomized trials.