Objective: Despite impressive advances in therapeutics in the last years, acute heart failure (AHF) remains a major cause of cardiovascular morbidity and mortality. Patients hospitalized because of heart failure (HF), irrespective of left ventricular systolic function, represent a high-risk population with limited short-term prognosis. A substantial component of HF-related mortality occurs during a hospital stay. In this study, we aimed to determine the factors impacting on in-hospital mortality in patients with AHF. Methods: During a 15-month period (December 2005-March 2007), 85 consecutive patients with (mean age: 64 8 years, male: 54%) an episode of AHF were included in this study. The effect of demographic, clinical, electrocardiographic, and echocardiographic characteristics, laboratory findings on in-hospital mortality were evaluated retrospectively. Results: Of 85 patients 24.7% of patients had new-onset HE Coronary artery disease (61%) was the most common underlying disease. The 44.7% of patients had hypertension, 37.6% had diabetes mellitus, 21% had chronic renal failure and 16.4% had chronic obstructive pulmonary disease. Left ventricular ejection fraction was 35 +/- 7%. In-hospital mortality rate was found as 11.7% (10 patients).The major cause of mortality was the progression of HF to cardiogenic shock in 60% of deaths. In comparison with surviving patients in terms of the clinical, demographic, electrocardiographic, and laboratory characteristics and left and right ventricular functions, patients died during hospitalization had higher blood urea nitrogen (45 +/- 20 mg/dl vs. 36 +/- 12 mg/dI, p=0.04), higher creatinine level (2.2 +/- 0.8 mg/dI vs. 1.1 +/- 0.5 mg/dI, p=0.001), and wider (IRS duration (130 +/- 13 ms vs. 116 +/- 18 ms, p=0.04) whereas they had lower plasma sodium level (128 5 mmol/l vs. 135 +/- 9 mmol/l, p=0.02) and systolic blood pressure (p=0.01). Logistic regression analysis revealed that plasma creatinine level (OR 1.5, 95% Cl 1.2 to 2.1, p=0.01), blood urea nitrogen (OR 2.1, 95% CI 1.8 to 3.1, p=0.001), plasma sodium level (OR 1.3, 95% CI 1.1 to 1.7, p=0.02), and systolic blood pressure (OR 2.2, 95% CI 1.9 to 2.8, p=0.01) were the independent predictors of in-hospital mortality. Conclusion: In-hospital mortality increases in patients who had lower systolic blood pressure, lower plasma sodium level, and renal dysfunction on admission.