Chronic hepatitis C virus (HCV) infection causes end-stage liver diseases and hepato cellular carcinoma. In the USA, Canada, and Japan, simeprevir – one of the second-generation HCV NS3/4A protease inhibitors – in combination with peginterferon α-2a or 2b plus ribavirin has recently been approved for HCV genotype 1-infected patients and is now used in daily clinical practice. This review summarizes the mechanism of action of simeprevir and the results of clinical trials of simeprevir and peginterferon plus ribavirin for HCV genotype 1 patients. In general, the simeprevir and peginterferon plus ribavirin treatment is highly effective and its adverse events are similar to those of peginterferon plus ribavirin only, the exception being milder, reversible jaundice. In the near future, the development of interferon-free regimens with simeprevir is expected. Careful attention should be paid to new results of clinical trials with simeprevir.