Aldosterone is elevated in heart failure and exerts multiple detrimental effects. In addition to playing key roles in sodium and volume regulation, aldosterone is involved in regulation of autonomic tone, endothelial dysfunction, tissue collagen turnover, myocyte fibrosis, and release of inflammatory modulators. Aldosterone receptor antagonists have proven to be a valuable treatment tool in the management of heart failure due to systolic dysfunction. Blocking the effects of aldosterone can improve many of the functions that are deranged in patients with heart failure, as well as promote excretion of sodium and water and preservation of potassium and hydrogen in the distal renal tubule. These medications can be especially effective at removing fluid from the periphery and soft tissues. Prevention of hypokalemia, which may predispose patients to arrhythmia, is an added benefit. Spironolactone and eplerenone are the two agents in this class that have been studied in patients with heart failure and left ventricular dysfunction. However, aldosterone antagonist therapy may not be appropriate for all patients with heart failure. Therefore, guidelines in managing patients on these medications should be followed to avoid serious electrolyte abnormalities and renal dysfunction. This review examines some of the mechanisms of action and the usefulness of aldosterone blockade in the management of heart failure.