Objective To study TIMI flow influence of intracoronary injection of GPⅡb/Ⅲa receptor antagonists (tirofiban) in patients with STEMI before primary PCI. Methods Sixty-seven STEMI patients (48 male, mean age 57.4?8.1 years old) admitted during April, 2005 to August, 2007 were included in the study and in all of them, IRA thrombus was found during CAG. The patients were divided into the primary PCI group (n=32) and primary PCI plus introcoronary tirofiban injection group (n=35). Changes in TIMI flow were were obsurved diving the operation. Results The incidence of slow-flow and no-reflow of the intracoronary tirofiban injection+PCI group was lower than that of the primary PCI group (2.86% vs 18.75%,P