Aldosterone is produced in the adrenal cortex and governs volume and electrolyte homeostasis. Hyperaldosteronism can occur either as primary aldosteronism (renin-independent) or secondary aldosteronism (renin-dependent). As the commonest cause of secondary hypertension, primary aldosteronism is associated with increased cardiovascular risk. Its most prevalent subtypes are aldosterone-producing adenomas as the most frequent unilateral form and bilateral hyperaldosteronism. Unilateral hyperplasia, familial hyperaldosteronism and aldosterone-producing carcinoma are rare. The aldosterone/renin ratio serves as a screening parameter for primary aldosteronism. If this ratio is elevated, confirmatory testing and adrenal imaging are performed. Adrenal venous sampling is considered the gold standard for the distinction of unilateral from bilateral disease. Unilateral disease can potentially be cured by adrenalectomy, whereas patients that are not candidates for surgery or have bilateral disease are treated with mineralocorticoid receptor antagonists. Over the past 10 years, somatic mutations in ion channels or transporters have been identified as causes of aldosterone-producing adenomas and so-called aldosterone-producing cell clusters (potential precursors of adenomas and correlates of bilateral hyperplasia, but also of subclinical hyperaldosteronism). In addition, germline mutations in overlapping genes cause familial hyperaldosteronism. Secondary hyperaldosteronism can occur in patients with hypertension treated with diuretics or in renal artery stenosis.