Chronic hepatitis C virus (HCV) infection is prevalent in the world, affecting 3% of the world's population. The current standard of therapy is pegylated interferon and ribavirin, reaching 54-63% of successful rates. In patients with HCV genotype 1 infection, a 48 week course of combination therapy has achieved a higher successful rate that a 24 weeks course of therapy. However, several studies in Taiwan have shown that a 24 week course of therapy has comparable or even better response to a 48 week course of therapy in Western countries. Therefore, whether a 48 week course of therapy can achieve a higher response to a 24 week course of therapy in Taiwanese patients with genotype 1 HCV infection remains unclear.