Background and Objectives: Angiotensin II receptor blocker (ARB) has emerged as an alternative to angiotensin converting enzyme inhibitor (ACEI) in the treatment of heart failure. This study was aimed to compare the effectiveness and safety of valsartan with ramipril in patients with heart failure, who were registered in Korea Congestive Heart Failure (KCHF) study. Subjects and Methods: Between Mar 2005 and Mar 2007, 82 patients (60.5짹12.4 years, 59 males) who complained of class II to IV dyspnea according to New York Heart Association (NYHA) classification and low left ventricular ejection fraction (EF) less than 50% were randomly allocated to valsartan or ramipril. After 6 months, clinical symptoms, vital sign, biochemical examinations and echocardiography were compared between two groups. Results: NYHA class (valsartan group: 2.31짹0.51 vs. 1.46짹0.58, p<0.001, ramipril group: 2.21짹0.55 vs. 1.61짹0.50, p<0.001) was improved in both groups. Cough incidence measured by cough index was significantly lower in valsartan group than in ramipril group (p=0.045). Left ventricular end-systolic dimension (49.6짹8.5mm vs. 43.5짹8.7mm, p<0.001) and end-diastolic dimension (60.4짹7.0mm vs. 56.9짹8.2mm, p=0.013) were decreased only in valsartan group. Conclusions: Valsartan was effective with relatively low adverse events in patients with heart failure compared with ramipril.