Twenty-four black men with mild to moderate essential hypertension were enrolled in an open-label trial comparing the efficacy of two doses of Capozide (captopril and hydrochlorothiazide). All antihypertensive drugs were discontinued and patients then received placebo for 2 weeks. Twenty-two patients, mean age 59.1 +/- 14.3 years, with sitting diastolic blood pressure (BP) 92 to 110 mm Hg, entered the 6-week active-drug phase. Eleven patients (Group A) were randomized to Capozide 25/15 and 11 (Group B) to Capozide 50/15. Baseline mean BPs were 151.0/100.7 mm Hg in Group A and 153.1/100.7 mm Hg in Group B. At week 6, mean BPs were 128.7/84.4 mm Hg in Group A and 126.8/82.7 mm Hg in Group B. Uric acid, blood urea nitrogen and creatinine levels rose slightly in both groups. There were no adverse events. Eighteen patients had normal BPs at study completion. Twice-daily Capozide treatment is effective and well tolerated in blacks; patients responded equally well to both doses.