Aim. To compare the efficacy and safety of chemical cardioversion (CCV) with refralon and amiodarone in patients with paroxysmal atrial fibrillation and flutter (AF/AFL).Material and methods. Fifty five patients (mean age, 65±11 years) with paroxysmal AF/AFL were included. All patients underwent a preliminary examination to rule out contraindications to CCV. Further, patients were randomized into groups of refralon (n=30) and amiodarone (n=28), respectively. CCV with refralon was carried out as follows: administration in doses of 5-5-10-10 µg/kg at intervals of 15 minutes. Patients of the second group were intravenously injected with amiodarone at a dose of 5 mg/kg of body weight for 20-60 minutes, depending on the drug tolerability. If AF/AFL persists after 60 minutes, infusion of amiodarone 100 mg/hour until restoration of sinus rhythm (SR) or reaching a dose of 1200 mg/day. Treatment efficacy was assessed by SR recovery, absence of AF/AFL recurrence, and arrhythmia relief time, and safety was assessed by detection of ventricular arrhythmogenic effects, bradyarrhythmias, blood pressure reduction, and QT interval prolongation. The follow-up period lasted 24 hours.Results. SR was restored in 96,7% (n=29) of patients in the refralon group, of which 56,7% (n=17) after a dose of 5 mcg/kg. In the amiodarone group, SR was restored in 57,1% (n=16) of patients (p<0,001). The arrhythmia relief time in the refralon group was 14 [7;23] min, while in the amiodarone group — 150 [82;240] min (p<0,001). There were no significant differences in the incidence of bradyarrhythmias, lowering blood pressure, and QT prolongation in the groups.Conclusion. Refralon demonstrates a higher efficiency and lower time to AF/AFL relief compared with amiodarone, while in most patients, SR recovery occurs after the administration of the lowest doses, which ensures CCV safety.