Angiotensin-converting enzyme inhibitors (ACE-I) have been proven to be effective in reducing morbidity and mortality in patients with heart failure or post-myocardial infarction left ventricular dysfunction. Despite evidence from several large-scale randomized trials, the use of ACE-I in patients with heart failure remains relatively low. In part, the failure to achieve more widespread use of ACE-I in patients with heart failure may be due to physician's perceptions of the side effects associated with ACE-I, such as angioedema, renal dysfunction, cough, and hypotension. Many of these side effects are thought to be due to ACE-I-induced bradykinin accumulation. It is possible to inhibit the effect of angiotensin II without increasing bradykinin levels using an angiotensin II type I blocking agent such as losartan. How effective losartan is compared with an ACE-I is uncertain, however. Some of the beneficial effects of ACE-I have been attributed to bradykinin accumulation, and therefore ACE-I might have an advantage compared with an angiotensin II type I receptor antagonist such as losartan. On the other hand, angiotensin II may be produced by non-ACE-I-dependent mechanisms, which would suggest that an angiotensin II type I receptor blocking agent would be advantageous. To determine the relative safety and efficacy of an ACE-I, which results in bradykinin accumulation and inhibitors of angiotensin II, versus an angiotensin II type I receptor blocking agent, which does not result in bradykinin accumulation, we have begun the Evaluation of Losartan In The Elderly (ELITE) trial, which will compare the safety and efficacy of captopril and losartan in elderly patients with heart failure.