Introduction: Acute Kidney Injury (AKI) is more common in critically ill children. Early identification and prompt management is needed as acute kidney injury is associated with poor outcome. It becomes essential for a reliable prediction tool to quantify the disease. Our goal was to study the mean platelet volume (MPV) and platelet distribution width (PDW) as a prognostic predictor of AKI in children. Material and Methods: A prospective observational study which included children aged 1 month to 12 years admitted to Paediatric intensive care unit(PICU) of a tertiary care teaching hospital, Madurai over a period of 1 year. Completebloodcountincluding Mean Platelet Volume and other laboratory investigations were measured and compared. P-RIFLE criteria was used to classify AKI severity. Results: A total of 342 children were included in the study. The incidence of AKI was 30.1%. Risk, Injury and Failure categories included 34%, 30% and 36% respectively.MPV value of <8.5 was associated with poor renal functions with sensitivity 71.3% and specificity 88.4%. AUC was 0.84 (95%CI, 0.80 – 0.88). Thrombocytopenia was not associated with poor prognosis in AKI. Conclusions: Our study reveals that increase in MPV is associated with poor outcomes in Acute kidney injury patients. Therefore, including MPV in risk quantification of AKI would be beneficial in managing patients.