Objective: The study aimed to analyze the impact of concomitant administration of P2Y12 inhibitors and PPIs on ischemia events in patients with acute coronary syndrome (ACS) after percutaneous coronary intervention (PCI). Methods: We retrospectively analyzed data from a international, multi-center registry between 2003 and 2014 in patients with ACS after PCI, grouped the cohort into patients receiving PPIs or no PPIs and assessed 1-year clinical endpoint (all-cause death/re-infarction). Meanwhile, we grouped the cohort into patients receiving clopidogrel or ticagrelor, and compared the impact of concomitant administration of PPIs and clopidogrel or ticagrelor on 1-year clinical endpoint. Results: Of 9 429 patients in the final cohort, 54.8% (n=5 165) was prescribed a PPI at discharge. Patients receiving a PPI were more likely to have comorbidities. No association was observed between PPI use and the clinical endpoint (HR 1.00, 95% CI 0.86-1.18). Meanwhile, no association was found between PPI use and the clinical endpoint in patients receiving either clopidogrel or ticagrelor. And the clinical endpoint in patients administrated of clopidogrel and PPIs had no difference with that of ticagrelor and PPIs. Conclusions: In patients with ACS following PCI, increased risk of ischemia event was not found in the concomitant use of PPIs and P2Y12 inhibitors, and especially, compared with ticagrelor, clopidogrel was found no association with ischemia events when concomitant administrated with PPIs.