In primary aldosteronism, cardio-cerebro-renal complication is higher in cases diagnosed after 5 years of onset of hypertension than those diagnosed before 5 years. Moreover, prognosis of hypertension and renal function after unilateral adrenalectomy for aldosterone-producing microadenoma with short-term exposure of hypertension is better than those for CT-detectable aldosterone-producing adenoma with long standing hypertension. Therefore, we should accurately diagnose PA among newly-onset hypertensive patients by simultaneous measurement of aldosterone and renin, and treat patients with aldosterone-producing microadenoma, which has been sometimes misdiagnosed as essential hypertension for a long time, by unilateral adrenalectomy, based on the diagnosis of adrenal venous sampling.