OBJECTIVES: The purpose of this study was to evaluate the efficacy and tolerability of monotherapy with the selective aldosterone blocker eplerenone in both black and white patients with hypertension. BACKGROUND: Essential hypertension and cardiovascular-renal-target organ damage is more prevalent in black than white adults in the U.S. METHODS: Black (n = 348) and white (n = 203) patients with mild-to-moderate hypertension were randomized to double-blind treatment with eplerenone 50 mg, the angiotensin II receptor antagonist losartan 50 mg, or placebo once daily. Doses were increased if blood pressure remained uncontrolled. The primary end point was change in mean diastolic blood pressure (DBP) after 16 weeks of therapy. RESULTS: Adjusted mean changes from baseline in DBP were -5.3 ± 0.7, -10.3 ± 0.7, and -6.9 ± 0.6 mm Hg in the placebo, eplerenone-treated, and losartan-treated groups, respectively (mean ± SE, p < 0.001 eplerenone vs. placebo, p < 0.001 eplerenone vs. losartan). In black patients, DBP decreased by -4.8 ± 1.0, -10.2 ± 0.9, and -6.0 ± 0.9 mm Hg for the placebo, eplerenone-treated, and losartan-treated groups, respectively (mean ± SE, p < 0.001 eplerenone vs. placebo, p < 0.001 eplerenone vs. losartan), whereas in white patients, DBP decreased by -6.4 ± 1.0, -11.1 ± 1.1, and -8.4 ± 1.0 mm Hg, respectively (p = 0.001 eplerenone vs. placebo, p = 0.068 for eplerenone vs. losartan). For reduction of systolic blood pressure (SBP), eplerenone was superior to placebo and losartan in all patients combined and in black patients, and was superior to placebo in white patients. Eplerenone was as effective as losartan in reducing SBP and DBP in the high renin patient, but more effective than losartan in the low renin patient. Similarly, eplerenone was at least as effective as losartan in patients with differing baseline levels of aldosterone. Both eplerenone and losartan were well tolerated. CONCLUSIONS: The antihypertensive effect of eplerenone was equal in black and white patients and was superior to losartan in black patients. © 2003 by the American College of Cardiology Foundation.