The purpose of the study was to assess the efficacy and tolerance of the beta1-selective beta-adrenoceptor-blocking agent bisoprolol in patients with chronic stable angina pectoris. A total of 236 outpatients (158 male and 78 female) over 21 years of age (mean age of 57 years and 60 years for men and women, respectively) were included in an open trial of 4 weeks duration. A total of 32.5% of the patients were smokers. After a washout period of at least 1 week, patients were initially treated with 10 mg of bisoprolol o.d. for 2 weeks, after which the dose could be adjusted to 5, 15, or 20 mg in accordance with clinical criteria (efficacy, tolerance). Eighty-eight percent of the patients were maintained on 10 mg of bisoprolol. The frequency of angina attacks was reduced in 89% of all patients: 56% became free of angina attacks. There were no differences in response as related to age and smoking habits. Bisoprolol was well tolerated. Beta-blocker-specific side effects were observed in 12 patients (5.1%). In conclusion, bisoprolol administered once daily appears to be an effective and safe antianginal agent.