Background: Recent data suggest that beta-blockers can be beneficial in patients with chronic heart failure (CHF). Atrial fibrillation (AF) is present in a significant number of patients with CHF and is associateing with significant morbidity and increasing mortality rates. Thus it is necessary to establish therapy to improve the poor prognosis in this highrisk population, but a specific benefit of beta-blockers to the subset with concomitant AF and CHF has been little demonstrated. Objective: To examine the effects of Bisoprolol (6 months treatment) on the ventricular function and hemodynamics in patients with AF and CHF. Methods: 84 patients with stable CHF(NYHA ≤ Ⅲ class)and AF were assigned to Treated Group( n = 37) or Control group Ⅰ ( n = 22, 24-hour heart mean rate ＜ 70/min) or Control Group Ⅱ ( n = 25, 24-hour heart mean rate ≥ 70/min). All patients were given the basic therapy for CHF, and Treated Group received Bisopolol. Clinical and echocardiographic variables were measured in 3 groups at baseline and after 6 months, and the results were compared. Results: After 6 months of treatment with Bisoprolol, left ventricular ejection fraction (LVEF) and NYHA class had significantly improved ( P ＜ O. 05), and a trend towards a reduction in combined end point of death or CHF hospitalization was also observed ( P ＜ 0.20) in Treated Group; The increase of LVEF in Treated Group were associated with a reduction in mitral regurgitation degree and left atrial volume; The heart rate in mean 24-hour and at peak exercise decreased in Treated Group, but were similar to that in Control Group Ⅰ . Conclusion: 6 months of Bisoprolol therapy resulted in an improvement in the NYHA class and LVEF, and also showed a trend towards a reduction in hospitalization or death. The beneficial effects of Bisoprolol on patients with AF and CHF may be partly mediated by improvement of ventricular diastolic function.