Response to statin therapy for cardiovascular disease is variable among different individuals. The authors aimed to investigate the effect of the CYP3AP1*3 polymorphism on the lipid-lowering efficacy of statins. They recruited 379 unrelated hyperlipidemic patients: 202 (103 men) treated with simvastatin and 177 (87 men) with atorvastatin as single-agent therapy (20 mg day(-1) orally) for 4 weeks. CYP3AP1*3(-44G>A) was genotyped using the PCR restriction fragment-length polymorphism method. Serum levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TGs) were determined before and after treatment. The frequency of the CYP3AP1*3 variant allele in Chinese hyperlipidemic patients was 70.6%. In the simvastatin treatment group, the percentage reduction of LDL-C level was greater in the CYP3AP1*3/*3 carriers than in the CYP3AP1*1 carriers. This difference was statistically significant for women but not for men. In contrast, the authors found no significant association between the lipid-lowering efficacy of atorvastatin and the CYP3AP1*3 polymorphism in all participants. However, in women, the percentage change of the TC level was significantly lower in the CYP3AP1*3/*3 carriers than in the CYP3AP1*1 carriers. These findings suggest that the CYP3AP1*3 allele may be a biomarker for the lipid-lowering efficacy of simvastatin and atorvastatin in Chinese women with hyperlipidemia.