Hepatitis C virus (HCV) infection is a global health problem, which may lead to chronic hepatitis, cirrhosis, hepatic decompensation and hepatocellular carcinoma (HCC). [1,2] Recently, treatment with peginterferon alfa plus ribavirin has become the standard of care for patients with chronic hepatitis C. While genotype 2 patients can have higher sustained virologic response (SVR) rates to 80-90%, genotype 1 patients generally have low SVR rates of only 40-50%. [3-5] In contrast, genotype 1 Taiwanese patients have superior SVR rates that those in Western countries. [6,7] Despite the overall improved response to this combination therapy, more than 75% of patients suffer from treatment-related adverse events and the costs remain high, [8,9] which make individualized therapy of paramount importance to maximize treatment response and minimize adverse events.