Abstract： Objective To observe the incidence of cardiovascular events in patients who are treated with percutaneous coronary intervention (PCI)combined with clopidogrel and omeprazole. Methods The clinical records of 249 patients with PCI were reviewed from May 2006 to October 2007.Clopidogrel and/or omeprazole were used as anti-platelet treatment,and the course of treatment was 30 days.The primary observation outcome was a major adverse cardiovascular event (MACE)which was defined as a composite of death,myocardial infarction and target vessel failure.Results During a mean follow-up period of 36 months,patients discharged with concomitant clopidogrel-PPI therapy had a MACE rate of 26.3％ (15/57)and 17.2％ (33/192)in the clopidogrel alone group (P＜0.05 ).Conclusions Concomitant use of clopidogrel and omeprazole in post-PCI patients is associated with a higher risk of MACE. Omeprazole may attenuate clopidogrel's beneficial antiplatelet effect which is crucial after PCI.Prospective randomized studies are warranted to provide definitive evidence for this interaction.