Angiotensin-converting enzyme inhibitors (ACE inhibitors) have been shown to be effective in improving symptoms and survival in patients with systolic left ventricular dysfunction. Despite their proven benefits the use of ACE inhibitors is still limited in many parts of the western world. In part, the underutilization of ACE inhibitors is due to the occurrence of side effects such as cough, renal dysfunction and first dose hypotension. These side effects are in part due to ACE inhibitor-induced bradykinin formation. Blockade of the effects of angiotensin II can however also be achieved with an angiotensin II type I receptor blocking agent such as losartan. To determine the relative safety and effectiveness of ACE inhibitors compared to an angiotensin II type I receptor blocking agent the evaluation of losartan and the elderly trial (Elite) is comparing the ACE inhibitor captopril to the angiotensin II type I receptor blocking agent losartan in elderly patients. When used ACE inhibitors are often given in doses lower than those shown to be effective in reducing mortality in the major randomized trials. Several trials are currently under way comparing low to high doses of ACE inhibitors which should provide information on the need to achieve the doses used in the major mortality studies.(ABSTRACT TRUNCATED AT 250 WORDS)