Approximately 40% of Japanese patients with essential hypertension, including low-renin hypertension, are inadequately managed. Low-renin hypertension generally responds poorly to angiotensin-converting enzyme inhibitors and angiotensin-receptor blockers, but may respond more optimally to diuretics, calcium channel blockers, and aldosterone blockers. This multicenter, randomized, double-blind, placebo-controlled, parallel-group, dose-ranging study evaluated the efficacy and safety of the selective aldosterone blocker eplerenone in 193 Japanese patients with essential hypertension. Although not a study inclusion criterion, baseline active plasma renin levels were consistently low (5.7-10.1 mU/L); most patients met the criteria for low-renin hypertension (< or =42.5 mU/L; normal range, 7-76 mU/L). Patients received placebo or eplerenone 50, 100, or 200 mg once daily for 8 weeks. Systolic blood pressure decreased significantly (-6.8 to -10.6 mm Hg vs. -2.1 mm Hg; p< or =0.0022 vs. placebo). Eplerenone offers significant blood pressure reduction with good tolerability in Japanese patients with hypertension, including those with low-renin hypertension.