Introduction. The onset of atrial fibrillation (AF) after open-heart surgical interventions is related to systemic and local inflammatory process. This is associated with the increases in the levels of inflammatory markers. Due to the anti-inflammatory properties of statins, statin therapy seems to be effective in the prevention of AF after coronary artery bypass grafting (CABG). However, other studies failed to demonstrate any antiarrhythmic effect of statins. Objective. To assess the role of statin therapy in the primary and secondary prevention of AF after GABG. Material and methods. A retrospective analysis of 225 medical records from the register of GABG interventions in 2013 was performed. The cases selected were divided in two groups. The first group included those patients who received no statin therapy and the second group included those patients who did receive statin therapy for at least three days prior to the operation and for all days postoperatively. A postoperative AF event was defined as an AF episode occurring in the first 6 days after surgery and lasting for more than 5 minutes. Results. The first group included 93 (41%) patients and the second group 132 (59%) patients. The rate of AF was 29% in Group 1 and 9% in Group 2 (p=0.0001). On Day 4 after surgery, leucocytes count was 10.9 (9; 13) in the first group and 9.1 (7,6; 10) in the second group (р=0.000002). On Day 1, leucocytes count was also lower in the second group but the difference was insignificant [9.5 (7.4; 12) vs 10.4 (7.5; 12.3), р=0.39]. AF paroxysms occurred earlier in the first group than in the second group [Day 2 (2; 3) vs Day 3 (3; 4.5), р=0.039]. An analysis of leucocytes count day-to-day changes was performed in a subgroup of patients who developed AF postoperatively. The analysis showed that peak leucocytes concentrations occurred on the day of onset of arrhythmia. In this subgroup, leucocytes count increased from 10.4 (7.5; 12.3) on Day 1 after surgery to 10.9 (9; 13) on Day 4 after surgery and to 12.3 (10; 14) on the day of onset of AF (р=0.0083; p<0.016 after application of the Bonferroni correction). The risk of occurrence of postoperative AF was evaluated using the Cox model of regression. «Prior AF» and «Statin use» were found to be statistically meaningful (р=0.002 and р=0.001, respectively; χ2=38.42, p<0.001). In accordance with the Cox model of regression, the risk of AF was 3.68 for «Prior AF» and 0.31 for «Statin use». Conclusion. In this study, statin therapy prior to and after GABG was found to be an effective method of prevention of AF in the early postoperative period. An anti-inflammatory property demonstrated by statins is one of the factors which may explain their antiarrhythmic effect.