Objectives: To investigate the early diagnostic value of neutrophil gelatinase-associated apolipoprotein (NGAL) on contrast induced nephropathy (CIN) in patients after percutaneous coronary intervention (PCI). Methods: A total of 200 patients received coronary angiography (CAG) and PCI in our hospital from 2016-01 to 2017-02 were enrolled and the research included in 2 groups: CIN group, 23 and Non-NCI group, according to 4:1 ratio, 92 patients without NCI. Serum levels of creatinine, blood and urine levels of NGAL were examined and compared at pre-operation and 4 h, 24 h, 48 h and 72 h after the operation between 2 groups. Results: All patients received CAG and CIN occurred in 23/200 (11.5%) patients. Compared with Non-CIN group, CIN group had more patients with elder age, more smokers and diabetes, P<0.05. Pre-operative blood and urine NGAL were both at normal level and it was similar between 2 groups, P>0.05. In CIN group, urine NGAL was significantly increasing at 4 h after operation and gradually increasing to 72 h after operation; blood NGAL was significantly increasing at 4 h after operation, it began decreasing at 24 h after operation and remained a relatively high level at 72 h after operation; post-operative blood and urine levels of NGAL were different from pre-operative condition at each time points, all P<0.05. In Non-CIN group, post-operative blood and urine levels of NGAL were similar to pre-operative condition, P>0.05. Post-operative blood and urine NGAL were different at the same time point between 2 groups, P<0.01. AUC of ROC for post-operative urine NGAL at 4h, 24h, 48h and 72h were 0.908, 0.926, 0.931 and 0.957 respectively, the sensitivity and specificity for CIN diagnosis were 91.3% and 100% at 4 time points; AUC of ROC for post-operative blood NGAL at 4 h and 24 h were 0.964 and 0.913, the sensitivity and specificity for CIN diagnosis were 87.3% and 100% at both time points. Conclusions: Blood and urine levels of NGAL may reflect renal function changes earlier than serum creatinine in CAG/PCI patients, it had the higher sensitivity and specificity for CIN diagnosis and could be used as the early predictor for CIN occurrence.