Background: Acute kidney injury (AKI) is associated with increased mortality in pediatric intensive care unit (PICU) patients. Early detection of AKI helps clinicians to manage promptly. Renal angina index (RAI) is established from changes in serum creatinine and condition of patients. Neutrophil-to-lymphocyte ratio (NLR) is calculated from a complete blood count (CBC). There are very few studies on the application of RAI and NLR in PICU. This study aims to evaluate the efficacy of RAI and NLR as AKI biomarker in PICU patients.Methods: A retrospective observational study was performed in 173 critically ill children, aged 1-15 yearsold, from August 2018 to November 2019. RAI and NLR were recorded on the day of PICU admission. The primary outcome was the diagnostic precision (sensitivity, specificity, negative predictive value (NPV) and summary receiveroperating characteristics (ROC) analysis) of RAI and NLR to predict subsequent AKI, AKI-requiring RRT and mortality within 28 days after admission to the PICU. Results:From the analysis of the 173 patients, RAI with a cutoff of 8 was associated with an area under the curve (AUC) of 0.71 in the ROC analysis with NPV of 98% to predict the subsequent AKI. The incorporation of NLR with a cutoff of 5.5 improved the performance of RAI, especially in the nonsurgical group to predict the needs for RRT, with an AUC of 0.88. Conclusion:RAI could be used as a reliable point-ofcare biomarker for the early detection of subsequent AKI. NLR improved the performance of RAI, especially in the nonsurgical group to predict the need for RRT.