The primary hyperaldosteronism (PHA) is the most prevalent form (8-10%) of secondary causes of hypertension among hypertensive subjects. This will result in 2 to 2.5 million people suffering from PHA in Germany. Screening for PHA should be performed by measuring the aldosterone-renin ratio in the morning. The current antihypertensive medication should be taken into account. A suspicious ratio must lead to a confirmatory test to validate the diagnosis of PHA. For further PHA subtype investigation adrenal imaging is performed using CT or MRI. Adrenal venous sampling is often required to definitively confirm uni- or bilateral aldosterone hypersecretion. The aldosterone-producing adenoma (Conn's syndrome) is primarily cured by endoscopical unilateral adrenalectomy. Bilateral hyperplasia, which is found in two-thirds of primary hyperaldosteronism, is treated primarily by a mineralocorticoid receptor antagonist (12.5-100 mg/day spironolactone). The start of medication should be closely monitored by serum electrolyte and creatinine controls.