The calcium antagonist drug, verapamil, was compared in double-blind, double-dummy, crossover studies with two beta-adrenoceptor blocking drugs, pindolol and labetalol. All were equally effective as antihypertensive drugs in patients with mild-to-moderate hypertension. Verapamil caused a fall in blood pressure by reducing total peripheral resistance, as judged by echocardiographic studies, and had no adverse effects on airways resistance in patients with obstructive airways disease. The favorable hemodynamic effects and absence of serious side effects suggest that verapamil may be an important advance in the treatment of hypertension.