20 patients with recent acute myocardial infarction （AMI） were divided intoperfosion group （12 cases） and non-perfusion group （8 cases）. All were performed by99mTc-MIBI SPECT imaging before thrombolytic therapy. The scintigraphy wasrepeated 5- 7 days later. SPECT was evaluated using an uptake score. The datashowed that the patency rate of infarct-related coronare atery was 66.7% and 50%respectively in AMI treated by urokinase within 6 and 6- 12 hours after onset.SPECT defect score was similar before thrombolysis in perfusion group andnon-perfusion group. SPECT defect score was significantly lower after thrombolysiscompared with before thrombolysis in reperfusion group （P< 0.05）. The percentdecrease of the uptake defects was 70.2 ± 10.8%. But SPECT defect score was similarbetween the 2 images in non-reperfusion group （P> 0.05）. It was concluded thatthrombolytic therapy can save dying myocardium and decrease the infarct size andalso improve heart function. Thereby

SPECT 99mTc-MIBI was a good method forevaluation of the infarct size and thrombolytic effects.