Aim: ST-segment elevation myocardial infarction (STEMI) is usually caused by a rupture in the atherosclerotic plaque, followed by platelet aggregation which ultimately leads to acute coronary artery occlusion. In this study, we investigated the effect of maintenance dose of Eptifibatide (intravenous drug of GP IIb/IIIa inhibitor) in patients with STEMI who underwent primary percutaneous coronary intervention (PPCI). Methods: 264 patients who had acute chest pain suggestive of STEMI were entered in the study. All patients received the same dose of bolus dose of eptifibatide. Then the patients were randomly divided into two groups, one group (n=147) received a maintenance dose of intravenous eptifibatide (infusion of 2g/kg/min) and the other group (n=117) did not receive this treatment. All patients were evaluated 1 and 3 months after the start of treatment in terms of predicted outcomes. Results: The occurrence of three-month MACE between the case and control groups did not have a statistically significant difference (28.6% versus 35.0% ; P-value: 0.286). Re-hospitalization occurred in 10 patients (6.8%) from the case group and 30 patients (25.6%) from the control group, which was statistically significant (P-value: 0.000). Also, investigations showed that the rate of re-infarction (P-value: 0.024) and target lesion revascularization (P-value: 0.003) was significantly lower in the group that received Eptifibatide infusion. Conclusion: Eptifibatide maintenance dose infusion in patients who undergo PPCI in the context of STEMI, does not significantly reduce MACE, although it does significantly reduce re-hospitalization and re-infarction. It also does not increase the risk of bleeding and cerebrovascular events.