Acute kidney injury (AKI) is associated with poor outcomes in adult and pediatric intensive care units (PICU). However, prevalence of AKI in critically ill patients was not well characterized, in part due to lack of an accepted definition. To address this, the Acute Dialysis Quality Initiative introduced the adult RIFLE criteria in 2002. Severity is stratified by relative increase in serum creatinine compared to baseline: “Risk” (1.5×), “Injury” (2×), and “Failure” (3×). Outcomes are stratified into “Loss” and “End stage renal disease” (ESRD). Multiple studies subsequently validated this RIFLE score and it quickly gained acceptance; this study sought to validate the criteria in children.