Background. It is unclear whether selective infarct-related artery (sIRA) administration of glycoprotein IIb/IIIa receptor inhibitors (GPI) may further improve myocardial reperfusion without increasing bleeding in patients with ST-elevation myocardial infarction (STEMI). The aim of this study was to compare the impacts of sIRA infusion with conventional intracoronary (IC) administration of GPI tirofiban on myocardial reperfusion and clinical prognosis in STEMI patients. Methods. A total of 203 consecutive STEMI patients within 12 hours of symptom onset were randomly assigned to receive tirofiban (10 mu g/kg body weight) through aspiration catheter (n = 107) or guiding catheter (n = 96) after thrombus aspiration, and following 12 hours of intravenous infusion (0.1 mu g/kg/min). The primary endpoint was the corrected Thrombolysis in Myocardial Infarction (TIMI) frame count (CTFC) after the procedure. The secondary endpoint was major adverse cardiac events at 30 days and 6 months. The safety endpoint was in-hospital bleeding, defined according to the TIMI bleeding classification. Results. Similar primary endpoints (CTFC of 28 +/- 17 vs 27 +/- 15; P=.841) were observed in the sIRA and conventional IC administration groups, respectively. The incidence of major adverse cardiac events (6.5% vs 5.2% at 30 days [P=.688] and 8.4% vs 7.3% at 6 months [P=.762]) and in-hospital major or minor bleeding (9.3% vs 8.3%; P=.800) were comparable in both groups. Conclusions. After thrombus aspiration, sIRA infusion of tirofiban does not improve myocardial reperfusion assessed by CTFC, as well as ischemic or bleeding events in this study.