The antianginal efficacy and safety of bevantolol was compared with placebo in 107 patients with angina pectoris of effort. The median frequency of angina attacks in these patients was 6 per week. Following a 6-week placebo-baseline phase, the patients were randomly assigned to groups receiving either 150 or 300 mg/day bevantolol (75 or 150 mg b.i.d.) or placebo for 6 weeks of double- blind treatment. During exercise tolerance testing at 2 hours postdose, the higher dose of bevantolol produced a marked increase in total work performed. Double product (HR × Systolic BP) at maximum common work load decreased significantly (p < 0.001) in both bevantolol groups compared with the placebo group. In patients receiving 300 mg/day bevantolol, the proportion who stopped exercising because of angina or S-T depression decreased from 97% to 65%; the frequency of angina attacks decreased by one-half or more in 77% of those with 3 or more attacks per week; and 90% had an improvement in capacity to per form usual daily and occupational activities. A significant therapeutic effect was still present 12 hours postdose. Bevantolol was safe; fewer adverse reactions occurred in either drug group than in the placebo group. Bevantolol appeared to be an effective, well-tolerated drug in the management of angina pectoris.