Betaxolol, a long-acting cardioselective beta-blocker, was tested alone and in combination with long-acting nitrates in a multicenter, double-blind, parallel, placebo-controlled study of 3 weeks duration in patients with stable angina pectoris. All patients underwent exercise tolerance tests (ETTs) using Bruce's protocol. During the 3- to 4-week single-blind placebo baseline phase, all other drugs except sublingual nitroglycerin and long-acting nitrates were withdrawn. Those patients (n = 115) whose time to onset of moderate angina was between 2.5 and 7.5 min and was within +/- 15% in 2 consecutive ETTs were randomized to betaxolol 20 mg/day (n = 54) or placebo (n = 53). Betaxolol, compared to placebo, increased time to onset of angina, time to 1 mm S-T segment depression, and total exercise time and decreased the double product, weekly anginal attacks, and sublingual nitroglycerin consumption (p < 0.01). Our results indicate that betaxolol given in fixed 20-mg daily doses was efficacious in stable angina pectoris and its combination with long-acting nitrates potentiated its effect.