Acute kidney injury (AKI) is one of the critical multiples after pediatric cardiac surgery. The diagnosis of post-operative AKI is usually established based on elevated serum creatinine. Novel, effective and early diagnostic markers of AKI are still needed to be established. The aim of this study is validate new and faster biomarkers for early diagnosis of AKI. The survey population composed of 30 children aged from week to 204 months with a mean of months = 43.08 ± 52.15. These children were subjected to cardiac surgery with cardiopulmonary bypass (CPB).Then they were divided into AKI and non-AKI subgroups according to the post-operative status. Surveillance of the patients was achieved by subsequent measurements of both plasma and urinary NGAL, serum creatinine (S.Cr) and serum urea levels at 2 hours (h) and 24 h, postoperative. Additionally, only serum creatinine and serum urea were measured at 48 hours post-CPB. No significant differences between both groups  concerning the S.Cr levels at baseline (p=0.572,AUC=0.566), 2 h (p=0.619, AUC=0.558) and 24 h (p=0.197, AUC=0.651) while a high significant difference was observed at 48 h post-operative (p<0.001 , AUC=1.000) .No significant differences between the two groups were detected concerning the serum urea levels at baseline (p=0.455, AUC=0.587), 2 h (p=0.113 , AUC=0.685) and 24 h (p=0.129, AUC=0.677) while a high significant difference at 48 h (p<0.001 , AUC=1.000). There was no significant differences concerning the plasma and urinary NGAL levels measurements at baseline (p=0.215) while a highly statistically significant difference was spotted at 2 h (p<0.001) and at 24 h (p<0.001). Plasma and urinary NGAL serve as early predictors of AKI before the elevation of S.Cr. in postoperative patients.