Aim. To study the level of high-sensitivity C-reactive protein (hsCRP) before coronary artery bypass surgery (CABG) and on days 7-10, as well as to assess the association of perioperative changes in hsCRP with the risk of postoperative atrial fibrillation (POAF).Material and methods. The study included 80 patients (71 (88,75%) men) who underwent an elective CABG in Cardiac Surgery Department of Sklifosovsky Research Institute of Emergency Medicine. The first episode of POAF was considered an episode of arrhythmia, registered by electrocardiography (ECG), Holter monitoring (HM) or bedside cardiac monitor in the intensive care unit. Depending on the development of atrial fibrillation in the postoperative period, patients were divided into 2 following groups: patients with POAF (n=20), patients without POAF (n=60). The serum level of hsCRP was studied twice: before surgery and 7-10 after CABG in patients of both groups.Results. Both groups did not differ significantly in the initial concentration of hsCRP (p=0,802). In the postoperative period, patients in both groups showed a significant increase in hsCRP compared with the initial concentration — up to 39,1 [19,6; 64,0] mg/l in the POAF group (p<0,001) and up to 29,3 [19,7; 45,6] mg/l in the group without POAF (p=0,001), but the difference between the groups was not significant (p=0,338). Serum hsCRP concentration at 7-10 days after CABG in patients of both groups was significantly higher than the baseline (p<0,001). However, no association between POAF risk and hsCRP concentration was found (p>0,05).Conclusion. In patients after CABG, on days 7-10, there is a significantly higher level of hsCRP compared with the initial concentration. There were no significant differences in the level of hsCRP between patients with and without POAF. The POAF of is not associated with an initially elevated level of hsCRP and hsCRP level on days 7-10 after CABG.