Primary aldosteronism (PA) is a common cause of arterial hypertension: in the PA Prevalence in Hypertensives (PAPY) Study, the prevalence of PA was 11.2% in consecutive referred hypertensive patients. When adrenal vein sampling (AVS) is available, two thirds of the cases can be attributed to a tumor and one third of cases are idiopathic; the opposite is seen when AVS is unavailable. Thus, AVS influences the relative prevalence rate of the main subtypes of PA. When adrenalectomy is undertaken based on AVS, almost 100% of patients are cured of hyperaldosteronism, one third are cured of hypertension, and 52% are markedly improved in terms of blood pressure control. Persistent hypertension can be predicted by a long history of hypertension and by the presence of excessive cardiovascular damage, including vascular remodeling. Therefore, an early diagnosis is crucial to achieve cure. This review discusses the implications of the high prevalence of PA for its diagnostic strategy.