1. Eight hypertensive patients with angina pectoris had placebo added to their existing medications for 8 weeks, then incremental doses of active labetalol with simultaneous stepwise reduction in other medicines until blood pressure was satisfactorily controlled; after that only labetalol and thiazide (8 weeks) and finally labetalol-placebo together with previous β-adrenoreceptor antagonists and thiazide for 4 weeks were administered.
2. During the labetalol plus thiazide period resting blood pressures and measurements obtained during isotonic exercise, isometric exercise and the cold pressor test were significantly lower than during the initial placebo addition period. Angina scores were significantly reduced during this period.
3. During the final treatment with placebo, β-adrenoreceptor antagonist and thiazide, blood pressures remained reduced, but angina was significantly worse.
4. Labetalol which antagonizes both α- and β-adrenoreceptors produced better relief of angina pectoris than β-adrenoreceptor antagonists during improvement in blood pressure in hypertensive patients.