OBJECTIVES: Previous studies have demonstrated the role of inflammation in acute heart failure. The neutrophil-to-lymphocyte ratio was found to be a useful inflammatory marker for predicting adverse outcomes. We hypothesized that an elevated neutrophil-to-lymphocyte ratio would be associated with increased mortality in acute heart failure patients. METHODS: The study cohort consisted of 167 acute heart failure patients with an ejection fraction <50%. The primary endpoint was in-hospital mortality, and the patients were divided into two groups according to in-hospital mortality. RESULTS: In a multivariate regression analysis, including baseline demographic, clinical, and biochemical covariates, the neutrophil to lymphocyte ratio remained an independent predictor of mortality (OR 1.156, 95% CI 1.001 - 1.334, p= 0.048). CONCLUSION: In conclusion, an elevated neutrophil-to-lymphocyte ratio seems to be a predictor of short-term mortality in patients with acute heart failure and a reduced left ventricular ejection fraction.