Background: Elevated neutrophil count during ST-segment elevation myocardial infarction (STEMI) is associated with adverse clinical outcomes. However, it is now known whether increased neutrophil count on admission directly reflects TIMI flow grade and left ventricular impairment after primary percutaneous coronary intervention (PCI). The aim of this study was to assess the relation between neutrophil count with basal and final TIMI flow, the left ventricular ejection fraction (LVEF), and one month major adverse cardiac outcome (MACE) after primary PCI. Methods: Eighty five consecutive patients with acute STEMI who underwent primary PCI were evaluated. Neutrophil counts were measured before PCI. TIMI flow grade before and after revascularization were evaluated during PCI. LVEF was assessed using Echocadriography (Acuson Secuoia C515, Siemens). Neutrophil counts obtained at admission were divided into tertiles: 1st(<7,000/���), 2nd,(7,000-11.000/���), and 3rd (>11,000/���). Clinical end points were assessed with one month MACE including cardiac death, non-fatal MI(NFMI), and target lesion revascularization (TLR) after primary PCI. Results: Patients with higher neutrophil tertile had worse basal TIMI flow (P=0.06) and significantly correlated with final TIMI flow (p=0.02). Neutrophil counts were inversely correlated with the LVEF (p=0.09). The patients with elevated neutrophil counts (3rd neutrophil tertile) was associated with increased 30-day composite cardiac death, NFMI and MACE (P<0.001, P=0.17, and P=0.001, respectively). Conclusion: Elevated neutrophil counts in patients with STEMI are directly related to myocardial injury and LV dysfunction and predict cardiovascular outcomes after primary PCI.