BACKGROUND: The early coronary reperfusion with tissue type plasminogen activator(t-PA) influenced on the short term mortality and long term mobidity in acute myocardial infarction. The attention for thrombolysis with t-PA has been focused in identifying the optimal t-PA regimen and on the possibility of achieving effective and safe thrombolysis with a bolus of t-PA. Experimental data demonstrates that rapid t-PA infusion resulted in improved thrombolysis with minimal fibrinogenolysis and without excessive bleeding than prolonged infusion. METHODS: Consecutive patients presenting up to 6 hour from the onset of symptoms were recruited for the study. Aspirin(200mg daily) should be given immediately, 100mg t-PA was administered as two intravenous bolus injections of 50mg t-PA each given 30 minute apart, and followed by 5,000 unit heparin IV bolus with continuous infusion for 5 days. Angiography was performed at 60 and 90min after the first bolus and between 12-24 hour after study entry. After 7-10 days of myocardial infacrtion, coronary angiograms were performed in all patients who had been taken ddouble bolus t-PA. RESULTS: At 60min, angiography revealed infarct-related coronary artery patency of TIMI flow grade 3 in 15(88%) of 17 patients. At 90min, infarct-related coronary artery patency of TIMI flow grade 3 was achieved in 16(94%) of 17 patients. Bleeding episodes were mostly minor(6 of 33 patients, 18%), and hemorrhagic stroke was developed in 1 patients(1/33, 3.0%). Three patients(9.0%) died in hospitalization probably due to ventricular rupture. CONCLUSION: The administration of 100mg of double bolus t-PA in acute myocardial infarcion results in remarkably high early TIMI flow grade 3 on infarct-related coronary artery patency rates(88% and 94% at 60 and 90min, respectively). The bolus injection of t-PA may be simple and effective strategy in the treatment of acute myocardial infarction. However, large numbers of prospective study would be required.