BACKGROUND AND OBJECTIVES: Angiotensin II receptor blocker (ARB) has emerged as an alternative to angiotensin converting enzyme inhibitor (ACEI) for the treatment of heart failure. This study aimed at comparing the effectiveness and safety of valsartan with ramipril in patients with heart failure, and these patients were hospitalized at Chonnam National University Hospital, Wonkwang University Hospital, Gunsan Medical Center, Presbyterian Medical Center, Seonam University Hospital and Gwangju Christian Hospital. SUBJECTS AND METHODS: Between March 2005 and March 2007, 82 patients (60.5+/-12.4 years, 59 males) who complained of class II to IV dyspnea, according to the New York Heart Association (NYHA) classification, and who had low left ventricular ejection fraction (LVEF) less than 50% were randomly allocated to valsartan or ramipril. After 6 months, the clinical symptoms, vital signs, biochemical tests and echocardiography were compared between the two groups. RESULTS: The NYHA class was improved in both groups (the valsartan group: 2.31+/-0.51 vs. 1.46+/-0.58, p<0.001; the ramipril group: 2.21+/-0.55 vs. 1.61+/-0.50, p<0.001). The incidence of cough, as measured by the cough index, was significantly lower in the valsartan group than in the ramipril group (p=0.045). The LVEF was improved in both groups (the valsartan group: 36.4+/-8.5% vs. 46.9+/-12.9%, p<0.001; the ramipril group: 35.1+/-8.5% vs. 45.3+/-11.2%, p<0.001). The improvements of the left ventricular end-systolic dimension (p=0.754) and end-diastolic dimension (p=0.998) were not different between the two groups. N-terminal Pro-B-type natriuretic peptide level was improved in both groups (the valsartan group: 2619.6+/-4213.5 vs. 995.4+/-2186.0 pg/mL, p=0.012; the ramipril group: 3267.9+/-4320.0 vs. 828.1+/-1232.8 pg/mL, p=0.009), and there was no difference between the groups (p=0.877). CONCLUSION: Both valsartan and ramipril were effective treatments, with relatively low adverse events, in patients with heart failure.