The blockade of the renin-angiotensin system in the heart failure using ACE inhibitors, based on numerous clinical studies, demonstrated significant decrease in morbidity and mortality in the patients. Discovery of angiotensin II receptor antagonists brought about a new possibility of blockade of the rennin-angiotensin system. The blockade of the renin-angiotensin system with angiotensin II receptor antagonists should have been more effective and comprehensive than that induced by ACE inhibitors. However, the first studies with angiotensin II receptor antagonists in heart failure did not confirm that the antagonists are superior in reducing mortality and hospitalization in patients with heart failure when compared with ACE inhibitors. For the time being, the ACE inhibitors remain the current therapy of choice in treating heart failure. Angiotensin II receptor antagonists are a reasonable alternative in patients who cannot be treated with ACE inhibitors because of adverse effects. Clinical studies currently under way with angiotensin II receptor antagonists may alter these conclusions.