The aim of the study was to investigate the effect of β-blocker treatment on a large cohort of patients with coronary artery disease in functional classes II and III according to the New York Heart Association (NYHA) classification. Among 11,575 patients with coronary artery disease screened for participation, but not included in the Bezafibrate Infarction Prevention (BIP) study, 3,225 (28%) were in NYHA classes II and III. In the latter group of patients we compared the prognosis of 1,109 (34%) treated with β blockers with 2,116 counterparts not receiving β-blocker therapy. After a mean follow-up of 4 years, all-cause and cardiac mortality rates were significantly lower among β-blocker users, 9% and 5%, respectively, than among β-blocker nonusers, 17% and 11%, respectively (p <0.01 for both). After multivariate adjustment, treatment with β blockers was associated with a lower all-cause mortality risk (hazards ratio [HR] 0.62, 95% confidence interval [CI] 0.49 to 0.78), and a lower cardiac mortality risk (HR = 0.61, 95% CI 0.45 to 0.83) than was no treatment with a β blocker. Lower total mortality risk was noted among patients in NYHA class II (HR 0.63, 95% CI 0.48 to 0.82) and in NYHA class III (HR 0.57, 95% CI 0.37 to 0.87) as well as in patients with (HR 0.62, 95% CI 0.48 to 0.81) or without (HR 0.70, 95% CI 0.45 to 1.09) a previous myocardial infarction. We conclude that β-blocker therapy in coronary patients in NYHA classes II or III is safe and associated with a lower risk for all-cause and cardiac mortality.