to identify factors associated with development of atrial fibrillation (AF) in the early postoperative period of coronary artery bypass grafting (CABG). A total of 376 patients with ischemic heart disease who underwent CABG were enrolled in the study. During the observation period AF occurred in 74 patients (19.7%, 93% men, mean age 64.0+/-6.4 years), an average of 3.6+/-2 days after surgery. Multivariate regression analysis showed that odds ratio (OR) for AF in patients with age >59 years was 1.5 (95% confidence interval [CI], 1.1-3.5; p=0.04), aortic cross-clamping time >43 min - 2.4 (95% CI, 1.05-6.2; p=0.03), left atrial dimension (LAD) >39 mm - 5.0 (95% CI, 2.0-12.6; p=0.0006), left ventricular ejection fraction (LVEF) <51% - 3.6 (95% CI, 1.6-8.3, p=0.002). During ROC - analysis the high sensitivity was observed for LAD >39 mm (82%, =0.001), high specificity - for LVEF <51% (80%, =0.0009), highest positive likelihood ratio for LVEF <51% - 2.56 (=0.0009), greatest negative likelihood ratio for LAD >39 mm - 0.31 (=0.001). In our study, the risk of AF development in the early postoperative period of CABG depended on the patients age, left atrial size, left ventricular ejection fraction, and aortic cross-clamping time during CABG.