Primary aldosteronism is the most frequent form of secondary hypertension. It is characterized by an autonomous, inappropriately high and unsuppressible production of aldosterone. The prevalence of aldosteronism in the general population is from 5-12% with bilateral adrenal hyperplasia and aldosterone-producing adenoma being the two main causes. Primary aldosteronism may either be sporadic or familial, the latter variant occurring in at least three forms: type I (or glucocorticoid-remediable aldosteronism), type II and type III. The diagnosis is based on the aldosterone/renin ratio as a screening test, subsequent confirmatory tests, and on CT/MR imaging studies. Adrenal vein sampling is the gold standard test for diagnosing the major subtypes and for identifying the surgically correctable forms. Genetic testing is used to exclude the familial forms.