Adverse reactions of simvastatin are mostly slight and transient, however, the incidence of simvastatin-induced hepatic impairment and myopathy are obviously higher in Chinese population than other racial groups. There is still lack of research data in Chinese. In this study, we will investigate whether there are specific genotypes which may predict the incidence of simvastatin-induced hepatic impairment and myopathy in Chinese so as to provide a basis for developing guidelines on precise medication in simvastatin therapy apply to Chinese population.