Acute kidney injury (AKI) is a common complication in patients undergoing coronary artery bypass grafting (CABG), which is associated with significant morbidity and mortality. This study identified echocardiographic predictors of AKI and determined whether these predictors were related to long-term mortality in CABG. This retrospective cohort study included 1,300 patients who underwent echocardiography before CABG at 2 tertiary referral centers from 2004 to 2010. The best echocardiographic predictor of AKI was determined using multivariate and stepwise selection methods. Patients were followed for 72 ± 28.8 months (maximum 11 years) for all-cause mortality. We measured the adjusted odds ratio and hazard ratio for AKI and all-cause mortality, respectively, according to the chosen parameter. E/e' was the best predictor of AKI among echocardiographic parameters. The high E/e' group (>15) exhibited a greater odds ratio for AKI (2.2 [1.51 to 3.27]) than the low E/e' group (<8). The high E/e' group required a longer hospital stay (16 days [12 to 23 days]) than the low E/e' group (14 days [11 to 17 days]). There were 272 deaths (21%) during follow-up. The high E/e' group exhibited a greater hazard ratio for long-term mortality (1.9 [1.34 to 2.76]) than the low E/e' group, and this difference remained statistically significant regardless of the occurrence of AKI and the size of the ejection fraction volume. E/e' in preoperative echocardiography is the best predictor of AKI and long-term mortality in patients undergoing CABG.