The ratio between the absolute number of neutrophils and the number of lymphocytes (NLR) has recently emerged as a potential new biomarker predicting worse clinical conditions ranging from infectious disease to cardiovascular disease. Prognostic significance of NLR in patients with ST-elevation myocardial infarction (STEMI) is not established. This study aimed to investigate prognostic impact of NLR in patients with STEMI.We analyzed the data and clinical outcomes of 30-day survivors with STEMI who received successful coronary intervention from 2006 to 2010. NLR was computed from the absolute values of neutrophils and lymphocytes from the complete blood count at admission. Occurrence of major adverse cardiovascular events (MACEs: death, recurrent MI, target vessel revascularization (TVR)) at 5 years was evaluated.We enrolled 326 patients and mean follow-up duration was 68 +/- 36 months. The mean NLR was 4.7 +/- 5.2. Among all patients, all-cause mortality occurred in 46 patients (14%). Initial NLR was higher in patients who experienced all-cause mortality (6.39 +/- 8.9 vs 4.2 +/- 3.1, P = .004). In a multivariate regression model, the higher NLR was independently associated with increased risk for all-cause mortality (Hazard ratio, 1.085: 95% confidence interval, 1.002-1.174, P = .044).Increased NLR was associated increased rate of all-cause mortality in 30-day survivors after index STEMI, who received successful coronary intervention.