Objective: Assessment of the role of statin therapy in the prevention of postoperative atrial fibrillation (POAF) after coronary artery bypass grafting (CABG) in patients without prior atrial fibrillation. Methods: A retrospective analysis of 206 patients, aged 57.2 ± 7.9 years (mean ± SD), who underwent isolated CABG is carried out. All patients are divided into two groups. The first group (nSt-patients) includes the patients who did not receive statin therapy prior to CABG (n = 82). The second group (St-patients) includes the patients who received statin therapy prior to CABG (n = 124). Both groups received the statin therapy from the first day after CABG. The risk of occurrence of POAF is evaluated using the Cox-regression model. Results: The rate of POAF was 25.6% in nSt-patients and 6.5% in St-patients (P = 0.020). On the 4th day after CABG, white blood cells (WBC) count was 11.0 (9.0, 13.0) × 109/mL (medians with inter-quartile ranges) in nSt-patients and 9.0 (7.6, 10.2) × 109/mL in St-patients (P < 0.001). The peak WBC numbers occurred on the day of POAF onset. The Cox-regression analysis shows that only two factors (statin therapy and number of grafts) had significant influence on the POAF onset. Odds ratio of POAF event prediction by statin therapy was 0.20 (95%CI: 0.08–0.51), P < 0.001. Each subsequent graft increased the risk of POAF in 2.1 times. Conclusion: Statin therapy carried out prior to the CABG is an effective approach to primary prevention of POAF in early postoperative period. Statin therapy after CABG in nSt-patients does not give prophylactic effect observed in St-patients.