AIM: To find out whether selective beta-adrenoblocker nebivolol can be used for heart rate (HR) control in patients with chronic tachysystolic atrial fibrillation. MATERIAL: Patients (n=20, 7 men, 13 women, age 47-79 years) with ischemic heart disease and permanent atrial fibrillation (duration 2.5 months - 11 years) admitted to a specialized clinic for diagnosis and treatment of cardiac arrhythmias. All patients had tachycardia throughout 24 hours despite therapy. METHODS: Dosing of nebivolol: week 1 - 2.5 mg/day, week 2 7 5 mg/day. If after 2 weeks HR was considered inadequate the dose was increased up to 7.5 mg/day. Holter ECG was registered at baseline and in the end of weeks 1 and 2 of treatment. RESULTS: After 1 week of nebivolol (2.5 mg/day) HR decreased: day-time average - from 116.3+/-13.4 to 97.2+/-14.5, day-time minimal - from 78.1+/-13,5 to 71.4+/-8.2, day-time maximal - from 154.4+/-18.1 to 142.1+/-15.5; night-time average - from 83.6+/-7.1 to 76.3+/-7.14, night-time minimal - from 61.2+/-6.7 to 56.6+/-5.1, night-time maximal - from 93.5+/-10.5 to 88.2+/-10.8 bpm. After week 2 when patients received 5 mg/day of nebivolol their HR was: day-time average - 79.6+/-9,8, day-time minimal -65.2+/-7.7, day-time maximal - 128.7+/-12,2, night-time average - 69.9+/-7.6, night-time minimal - 53.1+/-4,7, night-time maximal - 80.8+/-10.1 bpm. In 2 patients (10%), interruption of nebivolol was required because of atrioventricular block in evening and nocturnal periods. CONCLUSION: Nebivolol effectively controlled HR in hospitalized patients with chronic atrial fibrillation due to ischemic heart disease. In most patients 5 mg /day was sufficient for attainment of acceptable HR.