Resistant hypertension, defined as a persistent blood pressure over 140/90 mmHg despite the use of three antihypertensive agents including a diuretic, is unusual. The diagnosis requires ruling out initially pseudoresistance and a deficient compliance with treatment. Ambulatory blood pressure recording allow the recognition of white coat hypertension. When there is a clinical or laboratory suspicion, secondary causes of hypertension should be discarded. Excessive salt intake, the presence of concomitant diseases such diabetes, chronic renal failure, obesity, and psychiatric conditions as panic attacks, anxiety and depression, should also be wanted. The presence of target organ damage requires a more aggressive treatment of hypertension. Recent clinical studies indicate that the administration of aldosterone antagonists as a fourth therapeutic line provides significant additional blood pressure reduction, when added to previous antihypertensive regimens in subjects with resistant hypertension.