Objective :To explore influence of CYP2C19 gene polymorphism on clopidogrel resistance after percutane‐ous coronary intervention (PCI) in patients with coronary heart disease (CHD).Methods :A total of 100 CHD pa‐tients ,who were treated and received PCI in our hospital ,were selected .There were 24 cases with clopidogrel re‐sistance (CR ,CR group) and 76 cases without CR (NCR ,NCR group).According to CYP2C19 genotype ,patients were divided into rapid metabolism CYP2C19*1／*1 (n＝49) ,medium metabolism CYP2C19*1／*2 (n＝28) and*1／*3 (n＝11) ,and slow metabolism CYP2C19*2／*2 (n＝9) and *2／*3 (n＝3).Relationship among differ‐ent genotypes ,CR ,maximum platelet aggregation rate (MPA) and incidence of major adverse cardiovascular events (MACE) were analyzed .Results :With rapid metabolism CYP2C19*1／*1 as the base ,there was significant rise in CR risk in medium metabolism (CYP2C19*1／*2 and *1／*3 ,OR＝4. 16 ,5. 03 , P＜0.05 both) and slow metab‐olism (CYP2C19*2／*2 and *2／*3 ,OR＝7.04 ,17. 6 , P＜0.01 both ) ,medium metabolism increased by 4. 16 and 5. 03 times respectively ,while slow metabolism increased by 7. 04 and 17. 60 times respectively .Compared with rapid metabolism genotype ,there were significant rise in MPA and incidence rate of MACE in medium and slow me‐tabolism genotypes , P＜0.05 or ＜0. 01 ;incidence rate of MACE in CR group was significantly higher than that of NCR group (20. 8% vs.5. 3%, P＝0.02).Conclusion : CYP2C19 gene polymorphism possesses certain influence on CR after PCI in CHD patients .Those with medium or slow metabolism genotypes are more likely to suffer from CR ,higher MPA and incidence rate of MACE .