Aldosterone escape during chronic angiotensin-converting enzyme (ACE) inhibition may contribute to the high mortality among patients with heart failure. Aldosterone exerts several detrimental effects in the pathophysiology of heart failure. Spironolactone, an aldosterone antagonist, has proved beneficial when added to ACE inhibitors in patients with severe heart failure. However, spironolactone has substantial side effects mostly due to anti-androgen and anti-progestagen actions. This may limit its use in less severe heart failure. Recently, more selective aldosterone antagonists have been developed, which appear to have the same potential as spironolactone with fewer side effects. Trials to assess efficacy of these drugs in hypertension and mild heart failure are now being started.