This study examined the associations between the CYP3A4*1G, CYP3A4*22, CYP3A5*3 and PPARA rs4823613 A>G polymorphisms and the phenotypes of CYP3A estimated by the ratio of 6β-hydroxycortisol:cortisol in urine, and the low-density lipoprotein cholesterol response to simvastatin in Chinese patients with hypercholesterolemia.