The authors performed a long-term, double-blind, crossover, randomized study on the effects of two drugs (atenolol, 100 mg/day, or nifedipine, 10 mg t.i.d.) when administered alone or in combination on the exercise tolerance in 10 patients with stable angina on effort (mean age 52 +/- 4 years, 8 males and 2 females) and documented significant (greater than or equal to 70%) obstructive coronary lesions at angiography. None of the drug treatments improved exercise duration or maximal sustained work load. Atenolol decreased significantly ST segment depression to -1 +/- 0.8 from -1.91 +/- 0.7, baseline and -2.05 +/- 0.5, placebo. Nifedipine was not better than placebo. The atenolol plus nifedipine treatment was better than placebo (p less than 0.001) or nifedipine alone (p less than 0.05) but was not more significantly efficacious than atenolol alone. Long-term management of exertional angina can be usefully performed using atenolol. The use of nifedipine at the present dose of 10 mg, although well tolerated, did not improve the ST signs of ischemia.