This proposal is a phase II study that will evaluate the safety and efficacy of silymarin for the treatment of subjects with chronic hepatitis C who did not respond to conventional antiviral therapy. The primary objectives of this study are to assess the safety and adverse event profile of silymarin over a range of doses compared to placebo and to assess efficacy of silymarin in normalizing serum aminotransferase activity in patients with chronic hepatitis C. Secondary objectives are to characterize the effect of silymarin on serum levels of HCV RNA and to explore relationships between silymarin therapy and serum biomarkers of HCV hepatic disease activity (oxidative stress, apoptosis, and fibrogenesis).