Background: The benefit of angiotensin-converting enzyme (ACE) inhibitors on mortality in heart failure has been proved in randomized controlled trials. Methods: We prospectively evaluated the prescribing of ACE inhibitors and the prescribing of target ACE inhibitor doses in 43 ambulatory patients with heart failure to identify differences in ACE inhibitor utilization among elderly and nonelderly patients. The prescribed ACE inhibitor dose and other variables were assessed by direct patient interview and information contained in the medical record. Telephone calls were conducted at 3 months to identify the occurrence of clinical events. Results: Fewer elderly patients were prescribed target ACE inhibitor doses compared with nonelderly patients (21.4% vs 68.8%; p = 0.0136). Elderly patients were more likely to experience an event than nonelderly patients (11 vs 4; p = 0.0074). Elderly patients not receiving target ACE inhibitor doses demonstrated a trend toward more events than elderly patients who were at target doses. Conclusion: The data suggest that this group of elderly patients with heart failure who received lower ACE inhibitor doses appeared to be at higher risk for clinical events.