Background Primary percutaneous coronary interventions (PCI) have been proposed as a novel superior management strategy in patients with ST elevation myocardial infarction (STEMI) This study tested the hypothesis that in the acute phase of myocardial infarction with ST-segment elevation, the neutrophil/lymphocyte (N/L) ratio is a predictor of long term prognosis Methods We analyzed 551 consecutive STEM! patients treated with primary PCI at a single university center Patients were stratified according to quartiles of the mean neutrophil/lymphocyte ratio Results Kaplan-Meier survival analysis showed a cumulative eight year survival of 94 2% in the first quartile, 92 0% in the second quartile, 91 3% in the third quartile, and 75 4% in the fourth quartile (P <0 001 by log rank) Relative to patients in the other three lower N/L ratio quartiles patients in the highest quartile were more than four times more likely to die during hospitalization (P <0 001) and during long-term follow up (P <0 001) By multivariate Cox regression analysis including baseline demographic, clinical, and angiographic covariables, the N/L ratio in the highest quartile remained an independent predictor of mortality (hazard ratio 2 38, 95% confidence interval (CI) 1 42 to 3 98, P=0 001) Conclusion The neutrophil/lymphocyte ratio is a strong independent predictor of long term mortality after ST elevation myocardial infarction treated with very early revascularization