Objective To investigate the efficiency and safety of preoperational intravenous injection of tirofiban just before performing percutaneous coronary intervention (PCI) in emergency for myocardial infarction patients with acute ST-elevation myocardial infarction (STEMI). Methods Sixty cases with acute STEMI who were in accordance with our inclusion and exclusion criteria and received emergent PCI in our department from May 2011 to April 2013 were recruited in this study. They were prospectively divided into 2 groups by admission time, the group receiving intravenous injection of tirofiban before operation (observation group, n＝30), and the group receiving no tirofiban before operation (control group, n＝30). Basic information, forward blood flow of infarction related artery before and after operation, ST-segment resolution, serum cardiac markers and bleeding complications of the 2 groups were analyzed. Results There was no significant difference in basic clinical condition between 2 groups (P＞0.05). The forward flow of infarct-related artery was significantly different between the 2 groups before the operation (TIMI 0-1: 13 vs 15; TIMI 2: 12 vs 11; and TIMI 3: 5 vs 4, P＞0.05), but after the operation, the forward blood flow was significantly better in the observation group than in the control group (TIMI 0-1: 0 vs 2; TIMI 2: 2 vs 8; and TIMI 3: 28 vs 20, P＜0.05). No significant difference was found at the ST-segment resolution between the 2 groups [(77.32%±18.36%) vs (71.18%±19.22%), P＞0.05]. The value of serological heart muscle markers in 6h after the operation was significantly lower in the observation group than in the control group [creatine kinase MB (CK-MB): (118.4±55.8) vs (178.8±63.2)U/L, P＜0.05; and cardiac troponin T (cTnT): (2.18±0.69) vs (3.21±0.46)ng/L, P＜0.05]. There was no significant difference in the bleeding complications between the 2 groups after the operation (10.00% vs 6.67%, P＞0.05). Conclusion For emergent treatment of STEMI by performing PCI, preoperative intravenous injection of tirofiban improves postoperative myocardial perfusion, does not increase the risk of hemorrhage, and exerts great effect with sound safety in clinical application.