A 91-year-old depressed woman had resistant hypertension despite a triple combination of anti-hypertensives, including a Ca-antagonist, an angiotensin receptor blocker, and a thiazide diuretic at optimal doses. She had hypokalemic metabolic alkalosis, elevated plasma cortisol and ACTH, and elevated urinary cortisol. The high-dose dexamethasone did not suppress the elevated ACTH and cortisol. The addition of spironolactone to her previous medications controlled and normalized hypertension, hypokalemia, and hormonal abnormalities within 4 months. Her blood pressure, serum electrolytes, and the hormonal states remained normalized for more than a year thereafter. Her depressed mental state also improved after spironolactone.