Background: Initial TIMI grade and TIMI grade after PCI are known prognostic factor in STEMI patients. But, TIMI grade after passage of giudewire remained obscure. The aim of the study was to assess the correlation with prevalence of MACE and TIMI grade after passage in STEMI patients. Methods: We conducted a retrospective analysis of collected data on 198 consecutive patients (mean age 61.2 years, male 77%, HTN 39%, DM 20%) with intial TIMI grade O in STEMI patients between January 2006 and December 2010 at our center. We assessed demographic and clinical characteristics and echocardiographic and laboratory and coronary angiographic findings. The risk of MACE was also analyzed. The patients were divided into low TIMI flow grade group (TIMI flow grade 0 or 1 after passage of guidewire, n=143, 71.9%) and high TIMI flow grade group (TIMI flow grade 2 or 3 after passage of guidewire, n=56, 28.1%). Results: There was significant difference of MACE between low TIMI flow grade group and high TIMI flow grade group (23.2% vs 8.5%, P<0.05). Also, there were significant difference of prevalence of recurrent MI (14.3% vs 4.9%) and target lesion revascularization (TLR, 7.1% vs 0.0%) in both group. In target vessel revascularization (TVR) there was a little difference in both group (1.8% vs 1.4%). Conclusions: This study was showed that higher grade of TIMI flow after passage of guidewire compatible to less prevalence of MACE except death. This means that grade of TIMI flow after passage of guidewire might be a predictor of prevalence of MACE after PCI.