Purpose: Although angiotensin-converting enzyme (ACE) inhibitors are recommended for all patients with systolic heart failure, prior studies suggest that elderly cohorts are less likely to receive such therapy. The purpose of this study was to determine the age dependence of adherence to guideline-based medical care in hospitalized heart failure patients. Methods: We performed a multicenter observational cohort study including 613 patients admitted to participating hospitals with a primary diagnosis of heart failure with ejection fraction ≤40%. This cohort was divided into four age groups (group 1: <60, group 2: 60–69, group 3: 70–79, and group 4: 80 years) and adherence to guideline-based medical care was measured. Results: ACE inhibitors were administered to 83% of ideal heart failure patients, and this rate was similar for all age groups. Elderly patients received significantly lower ACE inhibitor dosages compared to their younger counterparts (168, 148, 125 and 117 mg captopril in groups 1, 2, 3, and 4, respectively, p = 0.001). Lower creatinine clearance (p < 0.001), prior residence in a long-term care facility (p = 0.037), intolerance to ACE inhibitors (p = 0.006), lower blood pressure (p = 0.005), absence of a history of hypertension (p = 0.005), and no prior heart failure hospitalizations within the past year (p = 0.001) were found to be independent predictors of low ACE inhibitor dosing. Conclusions: In this heart failure benchmarking project, elderly patients received guideline-based ACE inhibitor therapy at similar rates, but at lower doses, compared to their younger counterparts.