Abstract： Objective To explore whether antioxidant vitamin C infusion before procedure is able to affect the incidences of periprocedural myocardial injury or contrast-induced acute kidney injury(CI-AKI) in patients undergoing percutaneous coronary intervention(PCI) for cardiovascular disease. Methods In this prospective, singlecenter, randomized study, 532 patients were randomized into two groups: the study group, which received 3 g Vitamin C infusion over 6 h before PCI; control group received normal saline. The primary endpoint was PCI related myocardial infarction (MI). The secondary endpoint was CI-AKI and the post-procedure level of 8-hydroxy-2-deoxyguanosine (8-OHdG). Results After PCI, the peak levels of CK-MB and cTnI in study group were both significantly lower than those of control group. The incidence of procedure-related MI was reduced based on CM-MB or cTnI compared with control group (CM-MB: 6.8％ vs 12.7％, P=0. 021; cTnI: 20. 1％ vs 28.8％, P =0.020).The CI-AKI was also significantly lower in study group compared with control group(6.8％ vs 12.4％, P =0.029).The post-procedure plasma value of 8-OHdG was significantly lower than that of control group. Logistic multivariate analysis showed that pre-procedure use of vitamin C was independent protective factor for both procedure-related MI and CI-AKI ( MI: OR 0. 66, 95％ CI 0. 38-0. 91, P = 0.017; CI-AKI: OR 0. 64, 95％ CI 0. 27-0.89, P =0.024). Conclusion In patients undergoing elective PCI, pre-procedure intravenous treatment of Vitamin C can reduce the oxidation reaction in the plasma, the injury of myocardium and the incidence of CI-AKI.