Abstract： Objective To identify the clinical predictors of atrial fibrillation (AF) after coronary artery bypass grafting (CABG).Methods 322 consecutive patients who had undergone isolated CABG were reviewed. Preoperative, intraoperative and postoperative data were collected. Patients were grouped according to whether AF appeared postoperatively.Results AF occurred in 75 patients (23.3%). Most cases of AF (85.6%) appeared on or before the third postoperative day. The mean age for patients with AF was 62.5 years compared with 56.7 years for patients without AF (P<0.05). The mean aortic crossclamp time for patients with AF was 67 min compared with 60.3 min for patients without AF (P<0.05). The mean duration of cardiopulmonary bypass for patients with AF was 109.6 min compared with 97.3 min for patients without AF (P<0.05). The mean duration of mechanical ventilation for patients with AF was 19.1 h compared with 15.7?h for patients without AF (P<0.05). Multivariate logistic regression analysis was used to identify the following independent predictors of postoperative AF (P<0.05): age≥65 years (OR 2.7; 95% CI 1.5 to 5.1), lesions in the right coronary artery (OR 2.5; 95% CI 1.4 to 4.5), and early postoperative withdrawal of β blocker (OR 3.9; 95% CI 2.1 to 7.7).Conclusions AF remains the most common complication after CABG. Age and lesions in the right coronary artery can influence the incidence of AF, and β blocker and magnesium may be the most economical and effective prevention for AF early after CABG.Department of Cardiovascular Surgery, Fu Wai Hospital and Cardiovascular