Background: Nearly half of patients with heart failure showed preserved left ventricular (LV) systolic function (PSF). However, there is not much data of those patients in Korea. We compared clinical and other characteristics between the patients with PSF and the patients with LV systolic dysfunction (LVDF). Methods and Results: From Nov 2006 to April 2010, 421 patients (age: 68짹14 years, female 57.2%) newly admitted to Kangdong Sacred Heart hospital for acute heart failure were included in our study. PSF (LV ejection fraction ��� 40%) was present in 214 (50.8%) and isolated diastolic dysfunction was present in 43 (20.3%). PSF was associated with older age (70짹12 vs. 65짹15, P=0.001), female sex (67.8% vs. 46.4%, P<0.0001), history of hypertension (65.0% vs. 46.4%, P<0.0001), and lower levels of B-type natriuretic peptide (887.9짹941.7 vs. 1622.2짹1361.2 pg/mL, P<0.0001) compared with patients with LVDF. In-hospital mortality was lower in patients with PSF (2.5% vs. 11.8%, P=0.001). During a median follow-up time of 484 days, all-cause mortality was 18.3% for patient with PSF and 27.1% for patients with LVDF (P=0.032). In a model including clinical characteristics, echocardiographic measures, and BNP, the mortality was best predicted by medication with beta-blockers at discharge in patients with PSF (hazard ratio (HR) 2.30, 95% confidence intervals (CI) 1.04 to 5.12, P=0.04), whereas, by medication with angiotensin converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB) at discharge in patients with LVDF (HR 2.86, CI 1.34 to 6.10, P=0.007). Conclusion: Our study showed many differences exist between patients with PSF and patients with LVDF. Heart failure with PSF is associated with lower in-hospital and post-discharge mortality rate compared to those of patients with LVDF. The best predictor of mortality was use of beta-blockers in patients with PSF, whereas use of ACEI/ARBs in patients with LVDF.