Data from animal studies and clinical trials indicate that aldosterone causes cardiovascular and renal injury through mineralocorticoid receptor–dependent mechanisms. However, although aldosterone receptor antagonism reduces mortality in patients with congestive heart failure, the progestational and antiandrogenic side effects of the nonspecific aldosterone receptor antagonist, spironolactone, have limited its usefulness in the treatment of hypertension. This review provides an overview of the pharmacology, efficacy, and safety of a new, more selective aldosterone receptor antagonist, eplerenone, in the context of emerging concepts of the role of aldosterone in cardiovascular toxicity.