Aldosterone is a key cardiovascular hormone. Recent studies have illustrated its role in cardiac fibrosis and left ventricular hypertrophy as well as in impaired vascular reactivity. Moreover, many of these actions have been shown to be independent of its known effects on blood pressure. In a clinical setting, the benefits of aldosterone blockade in cardiovascular disease have been adequately demonstrated in recent large, randomised clinical trials. Aldosterone blockade was once limited by dose-related side effects, however, the introduction of a new, more selective, aldosterone receptor antagonist (eplerenone) has led to an increase in its use as a therapeutic strategy in cardiovascular disease. The role of aldosterone in hypertension has also been recently re-evaluated. As a result more widespread screening of hypertensive subjects using the aldosterone to renin ratio (ARR), the prevalence of Primary Aldosteronism (PA) is now estimated, albeit controversially, to be at least 10%. It is now accepted that screening for PA should be more widespread and not limited to those with hypokalaemia. Moreover, whilst there remains debate over the exact labelling of individuals with hypertension and raised ARR it is clear that such subjects have aldosterone levels inappropriate for the prevailing renin (aldosterone-associated hypertension). It is important that such individuals are identified since they can be offered more targeted treatment with selective aldosterone blockade or even surgery to control or normalise blood pressure.