Objective To investigate the incidence of acute kidney injury (AKI) in the elderly patients after cardiac surgery, and analyze risk factors and determine the early predictive value of serum neutrophil gelatinase-associated lipocalin (NGAL). MethodsTwo hundred and eighty-five elderly patients (≥ 60 years) who underwent elective cardiac surgery were recruited in this study. According to the occurrence of AKI or not, the patients were divided into AKI group (n＝81) and non-AKI group (n＝204). The predictive value of serum NGAL level in 2 h after surgery for AKI was evaluated with the area under receiver operating characteristic (ROC) curve. The risk factors of AKI were screened by logistic regression analysis. Results The incidence of postoperative AKI was 28.4% (81/285). The area under ROC curve of serum NGAL level in 2 h postoperatively for predicting AKI were 0.622. Multivariate logistic regression analysis identified that preoperative comorbidity of chronic kidney disease (CKD), intraoperative application of cardiopulmonary bypassing, perioperative infusion of large volume artificial colloids, high score of acute physiology and chronic health evaluation (APACHE) Ⅱ at the 1st day after surgery, and postoperative mechanical ventilation ＞24 h were independent risk factors for AKI. Conclusion The incidence of postoperative AKI remains high in the elderly patients after cardiac surgery. Early serum NGAL level has limited predictive value for the occurrence of AKI. Preoperative comorbidity of CKD, intraoperative application of cardiopulmonary bypassing, perioperative infusion of large volume artificial colloids, high APACHE Ⅱ score, and postoperative longtime mechanical ventilation increase the risk for AKI.