Background: The reported incidenc of AF after CABG surgery varies from 20 to 40%, with the arrhythmia usually occurring between second and fourth postoperative days. Postoperative AF after CABG was associated with greater in-hospital mortality and worse survival at long-term follow-up. Therefore, intensive attention has focused on the prevention of AF in high-risk patients. Many perioperative factors have been suggested to increase the incidence of postoperative AF after conventional CABG. In this study we are trying to examine some of these risk factors as predictors for Post-operative AF in our patients. In this study, our aim was to identify the perioperative predictors of AF in our patients who underwent Coronary Artery Bypass Grafting. Methods: Our Patients were divided into two groups; Group A included patients who did not develop PO AF (168 patients) and Group B patients who developed PO AF (84 patients). Perioperative Data, including gender, age, demographic variables and postoperative morbidity and mortality were extracted from the medical records. Results: This retrospective cohort study was conducted on 252 consecutive adult patients underwent CABG, in King Faisal Specialist Hospital and Research Center in Jeddah, Saudi Arabia. The mean age for patients with PO AF was 65 years (P = .0001). Eight-three patients (49.4%) were diabetics in group A and 56 patients (66.7%) in group B (P = .0001). Patients who developed POAF had a lower ejection fraction (44.8 ± 5.7%) (P = .0001), diastolic dysfunction (P = .0001), Larger Left atrial volume (P = .0001). Bleeding requiring re-opening for exploration and Postoperative shock were identified as significant predictors for POAF. Multivariate logistic regression (odds ratio, ±95% CI, P value) was performed to identify the effect of age, preoperative heart rate, ejection fraction, postoperative bleeding, Shock, ventilator time, Sensitivity was 89.5%, specificity was 94.6%, positive predictive value was 89.5%, and negative predictive value was 94.6%. Conclusion: In our study, advanced age, enlarged LA volume, low ejection fraction, combined surgeries and prolonged ventilation time were found to be predictors of atrial fibrillations after coronary artery bypass grafting. Keywords: Atrial fibrillation; CABG; Postoperative outcome; Predictors