Aldosterone receptor antagonists (ARAs) are becoming important supplementary options in the pharmacologic treatment of congestive heart failure (CHF), and the indication for ARAs continues to grow. Aldosterone is a stimulator of myocardial fibrosis, causing progression of CHF and serving as an important factor in the pathogenesis of diastolic heart failure (ie, heart failure with normal ejection fraction). The beneficial effects of ARAs have already been demonstrated in patients with severe CHF and patients with symptoms of CHF and left ventricular dysfunction early after myocardial infarction. ARAs may also be important in mild to moderate CHF, but current evidence has not been convincing. More is to be expected from the potential role of ARAs in heart failure with normal ejection fraction and perhaps in atrial fibrillation. It is hoped that the results of large randomized clinical trials further elucidate the indications of ARAs beyond current guidelines.