Abstract: Objective: To investigate the efficacy and safety of tirofiban in the treatment of patients receiving primary percutaneous coronary intervention( PCI) for acute ST-segment elevation myocardial infarction( STEMI). Methods: The clinical data of 100 patients with acute STEMI were analyzed retrospectively. Fifty of them( control group) received dual antiplatelet therapy( DAPT)( aspirin and clopidogrel) before and after primary PCI,and the other fifty( experimental group) received trigeminy antiplatelet therapy( aspirin, clopidogrel and tirofiban) till 48 hours after primary PCI. Results: At 30 days,the incidence of major adverse cardiovascular events includingcardiac death,non-fetal MI,target vessel revascularization and severe unstable angina in the experimental group was 4. 0%, which was significantly lower than the 18. 0% in the control group( P 0. 05). From 48 hours up to 30 days,the incidence of minor bleeding and thrombocytopenia had no significant difference between the two groups( P 0. 05). No major bleeding occurred in either group. Conclusions: Adding tirofiban to DAPT could safely decrease the incidence of 30 day MACE in patients with STEMI undergoing primary PCI.