Background Tirofiban has been widely used as an adjunctive pharmacologic agent for revascularization in patients undergoing percutaneous coronary intervention,and the outcomes appear attractive.However,the potential benefits from early administration of tirofiban in patients with acute ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI) remain unclear.Methods We conducted a search in MEDLINE,EMBASE,and the Cochrane Central Register of Controlled Trials up to September 2012 without language restriction.A total of eight randomized trials (n=1 577 patients) comparing early (emergency department or ambulance) versus late (catheterization laboratory) administration of tiroflban in STEMI patients undergoing PPCI were included in this meta-analysis.Risk ratio (RR) was computed from individual studies and pooled with random-or fixed-effect models.Results There were no differences in post-procedural Thrombolysis In Myocardial Infarction (TIMI) flow grade 3 and Corrected TIMI Frame Count (RR=1.02,95％ confidence interval (C/):0.99-1.05,P=0.18; weighted mean difference (WMD)=-0.93,95％ CI:-5.37-3.52,P=0.68,respectively) between the two groups.Similarly,there were no significant differences in the incidence of 30-day mortality (RR=1.69,95％ CI:0.69-4.13,P=0.25) and re-myocardial infarction (RR=0.71,95％ CI:0.21-2.35,P=0.57) between early and late administration of tirofiban.As to the safety end points,no significant difference was observed in hospital minor bleeding (RR=1.08,95％ CI:0.54-2.14,P=0.83) and hospital and 30-day major bleeding between the two groups (RR=0.98,95％ CI:0.46-2.10,P=0.96; RR=1.32,95％ CI:0.59-2.97,P=0.49,respectively).Conclusions Early administration of tiroflban in patients undergoing PPCI for STEMI was safe,but no beneficial effects on post-procedural angiographic or clinical outcomes could be identified as compared with late administration.Besides the negative finding,more high-quality randomized clinical trials are still needed to explore the efficacy of adequate,earlier administration of tirofiban in patients undergoing PPCI.