Objectives: We sought to analyze the value of measuring atrial electromechanical interval (AEMI) in predicting post coronary artery bypass grafting (CABG) atrial fibrillation (AF). Background: Atrial fibrillation is the most common arrhythmia after CABG with as many as 10–40%. Several predictors are associated with the development of AF after cardiac surgery. Methods: At least 30 patients; 18 males and 12 females (mean age 53 + 12 years) with ischemic heart disease diagnosed by coronary angiography and underwent CABG enrolled in the study. Pre-operative data were collected including laboratory, 12-lead ECG to measure P wave duration and P wave dispersion, trans-thoracic echocardiography to measure LV dimensions, ejection fraction, and LA volume. Pre-operative tissue Doppler imaging (TDI) was used to measure atrial electromechanical interval (AEMI) in milliseconds from the onset of P wave on the surface electrogram till the onset of atrial systole (Am). Results: Our patients were classified into two groups, group I with documented post CABG AF and group II with no AF. It was found that the mean value of AEMI in group I patients was significantly longer; 136 + 5.6 vs 93.7 + 19 ms in group II patients (P < 0.001). Using receiver operator characteristic (ROC) analysis, it was found that the cutoff value of AEMI as a predictor of post CABG AF was 120 ms which achieves 100% sensitivity and 99% specificity. It was found also significantly increased P wave duration and dispersion in group I patients compared to group II (97.7 ± 3 vs 94 ± 3.9 ms; P = 0.02 and 26 ± 4.7 vs 23 ± 4.7; P = 0.04, respectively). Conclusion: using AEMI as a predictor of post CABG AF is a valuable marker which carries high sensitivity and specificity.