The cardioselective beta adrenoceptor blocking agent metoprolol was compared with the calcium antagonist verapamil in relation to effects on angina pectoris. Twenty patients with stable, exercise-induced angina pectoris took part in a 14 week study that began with a 4 week single blind placebo period. In the succeeding 4 weeks, verapamil in a daily dose of 360 mg or metoprolol, 200 mg twice daily, was administered in double-blind fashion. After 2 weeks the patients were transferred to a second 4 week period of treatment with the other drug. The number of anginal attacks and the consumption of nitroglycerin tablets were reported. At the end of each treatment period a symptom-limited maximal exercise test was performed. The mean daily rate of anginal attacks and nitroglycerin consumption decreased significantly (p less than 0.01) and to a similar extent with both drugs. Exercise capacity increased from 103 +/- 7 to 113 +/- 7 watts (p less than 0.01) with metoprolol and to 119 +/- 6 watts (p less than 0.01) with verapamil. The increase with verapamil was significantly higher (p less than 0.05) than with metoprolol. Metoprolol caused a substantial reduction in the rate-pressure product both at rest and during exercise (p less than 0.001); this variable was not influenced by verapamil. Adverse effects were only mild to moderate and did not cause the cessation of treatment in any case. In conclusion, metoprolol and verapamil are two effective drugs for treatment of stable exercise-induced angina pectoris. Which drug is preferable as a first choice may depend on possible contraindications to one of these agents rather than on the belief that one is much more effective than the other.