Background: Gene variants contribute to variability in individual responsiveness to clopidogrel and influence cardiovascular outcomes in Caucasian patients with acute coronary syndrome (ACS). However, limited data is available in Asian populations. Methods: We resequenced 14 genes in metabolizing and activity pathway of clopidogrel in 138 patients with ACS and prospectively assessed the modulating effects of 13 variants possibly related to clopidogrel efficacy on one-year cardiovascular event occurrence in 5820 ACS patients after percutaneous coronary intervention (PCI). In addition, platelet aggregation rate was measured in 1084 participants and plasma levels of active metabolite were determined in 15 patients to test whether increasing clopidogrel maintenance doses increases active metabolite exposure. Results: No significant associations were found between any of the tested variants and risk of cardiovascular events (P > 0.05), although CYP2C19*2 carriers had slightly higher on-treatment platelet aggregation rate and lower active metabolite exposure compared with that of non-carriers (Median [IQR] 51.49 [35.43-66.75] vs. 49.05 [32.36-63.38], P = 0.012) (means +/- SD AUC, 22.84 +/- 5.00 vs. 35.05 +/- 12.34, P = 0.008). Switching from 75 mg daily clopidogrel to 150 mg daily fully overcomes low exposure to clopidogrel active metabolite in CYP2C19*2 carriers (means +/- SD AUC, 32.35 +/- 8.65 vs. 35.05 +/- 12.34, P = 0.314). Conclusion: Different from Caucasian populations, genetic variants have no significant influence on clinical outcomes and have much milder effects on inhibition of platelet and active clopidogrel metabolite levels in Chinese patients with ACS after PCI, an effect which could be overcome with a dose escalation to 150 mg daily. (C) 2017 Published by Elsevier Ireland Ltd.