Iron is essential to the production of myocardial energy and proteins critical for cardiovascular function. Nearly 50% of patients with heart failure with reduced ejection fraction (HFrEF) meet current criteria for iron deficiency, and there has been considerable interest in intravenous repletion of iron stores as a therapeutic strategy to improve HFrEF outcomes. However, the data on intravenous iron therapy in HFrEF have been mixed.