Several well-controlled trials in patients with heart failure have shown that the use of angiotensin-converting enzyme (ACE) inhibitors, in combination with a diuretic, causes a reduction in mortality and morbidity, which seems to be mainly due to a reduction in fatal and nonfatal cardiovascular events. Our aim was to determine whether 249 consecutive patients discharged from hospital with a primary diagnosis of heart failure were routinely being treated with an ACE inhibitor at an appropriate dose. At the time of admission to hospital, 91 (36.5%) were receiving a combination of a diuretic and an ACE inhibitor, 129 (51.8%) were receiving a diuretic alone, and 29 (11.6%) had not previously received either a diuretic or an ACE inhibitor. At the time of discharge from hospital all patients were on a diuretic and 144 (57.8%) were also receiving an ACE inhibitor. Although 41 patients (16.5%) had a relative or absolute contraindication for the use of an ACE inhibitor, 64 patients (25.7%) with no contraindication were not receiving an ACE inhibitor. Many of the patients who were prescribed an ACE inhibitor were given it at an inappropriate dose; only 24 patients (16.7%) were on the dose that was used in the clinical trials showing a reduction in mortality. These results show that in one in four patients admitted to hospital with heart failure who should be receiving an ACE inhibitor by the time of discharge, are not. The average age of these patients was 76 years. Whilst it has been shown that the benefit of ACE inhibitors does not appear to be age-related, most published studies have not included many patients over the age of 80. Specific studies looking at the effect of ACE inhibitors in elderly patients would be helpful, as well as studies to determine the optimum treatment regimen for this age group.