Background. Heart failure places a burden on patients and health care systems worldwide. Although the advent of angiotensin-converting enzyme (ACE) inhibitors markedly improved management of this chronic disorder, treatment is still not optimal, and morbidity and mortality remain high. Objective: This review summarizes existing data on losartan, an angiotensin II (AII)receptor antagonist, and compares its potential role with that of ACE inhibitors in the management of patients with heart failure. Methods: Relevant primary studies and review articles were identified through a MEDLINE search of the English-language literature for the past 5 years and through examination of the reference lists of the articles so identified. Search terms included, but were not limited to, angiotensin-converting enzyme inhibitors, angiotensin II-receptor antagonists, and losartan. Results: Preclinical and clinical studies of losartan have demonstrated consistent hemodynamic effects (via selective antagonism of the All type I receptor) and a safety profile similar to that of placebo (presumably a reflection of the selective approach to AII blockade). In addition, large-scale end-point studies have shown losartan to have comparable efficacy to ACE inhibitors on a number of morbidity and mortality measures. Conclusions: There is strong evidence for the broad applicability of AII-antagonists in heart failure and for the use of AII-antagonists in the treatment of a broader population of patients with heart failure, not only those who are unable to tolerate treatment with ACE inhibitors.