A new dosage form of lappaconitine hydrobromide has been created – the long-acting drug Allaforte®, which has fewer side effects compared to the traditional dosage form (Allapinin®). Objective. To evaluate the effectiveness, safety and tolerability of Allaforte® therapy in comparison with the drug Rytmonorm® in patients with paroxysmal atrial fibrillation (AF). Material and methods. Patients who met the inclusion criteria and those who did not meet the non-inclusion criteria were randomized into 2 groups: 1st (n=50) – patients received Allaforte® 25 mg 3 times a day with an increase in dose to 50 mg 2 times a day when detected attack of AF; 2nd (n=50) – patients received Rytmonorm® 150 mg 3 times a day with an increase in dose to 300 mg 2 times a day if an attack of AF was detected. Results. The average time from the first dose of the drug to the development of AF paroxysm in the 1st group (Allaforte®) was 98.877±6.022 days, in the 2nd group (Rytmonorm®) – 98.808±5.876 days, the average time from the first dose of the drug to the completion of the study – 105.740±5.032 and 103.732±5.353 days, respectively. The drugs Allaforte® and Rytmonorm® equally improved the quality of life of patients. A comparative analysis in groups according to the severity of adverse events and their cause-and-effect relationship with the drug did not show significant differences. Conclusion. The study drugs showed comparable effectiveness in preventing attacks of AF with similar safety and tolerability.