The efficacy and safety of nitrendipine in oral doses of 5-40 mg twice daily, alone or in combination with hydrochlorothiazide (50-150 mg/day) and/or propranolol (40-120 mg/day), were evaluated in an open study of 50 patients with severe hypertension with supine diastolic blood pressure (BP) greater than 115 mm Hg. Forty-six patients with an initial mean supine BP of 190/120 +/- 21/8 reached 151/95 +/- 15/6 mm Hg at visit 9, and 40 patients with a baseline BP of 188/120 +/- 21/9 achieved mean BP of 142/87 +/- 15/7 mm Hg at the end of therapy (visit 16). Thirty (75%) of these patients were normotensive: 9 (22%) on nitrendipine alone, 3 (7.5%) on nitrendipine and hydrochlorothiazide, 7 (17.5%) on nitrendipine and propranolol, and 11 (27.5%) on triple therapy. In nine responders to nitrendipine alone, mean BP was reduced from 187/119 to 143/84 mm Hg. Mean standing BPs were similarly decreased. Initially, heart rate increased slightly but decreased to baseline at the end of therapy. Side-effects were generally mild to moderate and were attributable to vasodilatory effects of the drug. Three patients required drug discontinuation because of adverse effects. Addition of propranolol and hydrochlorothiazide was well tolerated. Nitrendipine (20-40 mg twice daily) alone or in combination with propranolol and hydrochlorothiazide offers an alternative therapeutic approach in the management of severe hypertension.