Abstract: AIM:To assess the safety and efficacy of tirofiban in different periods of thrombolysis in acute myocardial infarction. METHODS: Eighty-seven patients with ST-segment elevation myocardial infarction (STEMI) were randomly divided into three groups: routine thrombolysis group (thrombolysis only, n=30), pre-treatment tirofiban group (tirofiban before thrombolysis, n=28) and rescue tirofiban group (tirofiban after thrombolysis failure, n=29). The perfusion indirect indexes of thrombolysis were observed in the three groups. Major cardiovascular complications in 24 h and hemorrhagic events were also observed. RESULTS: Rapid reperfusion was observed in the pre-treatment tirofiban group. Peak value and peak time of cardiac troponin I (cTNI), creatinine kinase and MB isoenzyme (CK-MB) in the pretreatment tirofiban group were lower and shorter than those in the routine thrombolysis group and rescue tirofiban group. Administration of tirofiban before or after thrombolysis more effectively shortened the duration of chest pain and lessened the ST segment descent compared with those in the routine thrombolysis group. But no signifcant difference was found in hemorrhage events and cardiovascular complications during 24 h among the three groups. CONLUSION: Tirofiban combined with thrombolysis, especially administration of tirofiban before thrombolysis, could improve the success rate of thrombolysis and lessen the myocardial injury without increasing cardiovascular complications and hemorrhage risks.