Background: Atrial fibrillation (AF) is the most common cardiac arrhythmia following coronary artery bypass grafting (CABG). We hypothesized that measures of left atrial (LA) function would be useful in predicting AF in patients undergoing CABG. Methods and results: In the study, 611 patients were included after CABG. All patients had echocardiograms performed preoperatively and LA functional measurements were assessed. These measurements were LA maximum volume index (LAVmax), LA minimum volume index (LAVmin) and LA emptying fraction (LAEF). The endpoint was AF occurring >14 days after surgery. During the follow-up period of a median of 3.7 years, 52 (9%) developed AF. The mean age was 67 years, 84% were male and the average left ventricle ejection fraction was 50%. Patients who developed AF had a lower CCS class and lower LAEF (40 vs. 45%), otherwise no clinical differences were observed between outcome groups. No functional LA measurements were significant predictors of AF in the whole CABG population. However, in patients with normal-sized LA (n = 532, events: 49), both LAEF and LAVmin were univariable predictors of AF. When the functional measurements were adjusted for the CHADS₂ score, both LAVmin (HR = 1.07 [1.01-1.13], p =.014) and LAEF (HR: 1.02 [1.00-1.03], p =.023), remained significant predictors. Conclusion: No echocardiographic measurements were significant predictors of AF after CABG. In patients with a normal LA size, LAVmin as well as LAEF were significant predictors of AF.