Background: Acute kidney damage (AKI) is frequent in clinical practice, as a result of an injury or infection sustained before to hospital admission, or it can be acquired in the hospital. AKI is a frequent diagnosis in hospitalized patients, especially in the critically ill and at least occasionally in children who are not critically ill. When patients initially arrive with uremia in clinical practice, it is frequently necessary to accurately diagnose acute or chronic kidney failure, especially in developing nations without a reliable medical record-keeping system. The diagnosis is made simpler if evidence of chronic kidney disease (CKD) is present. Hyaluronic acid may be a biomarker CKD patients Aim: To differentiate AKI from CKD by estimating serum level of hyaluronic acid (HA). Also, to predict chronicity for AKI. Patients and methods: This case control study was conducted on on children with CKD on HD chronic kidney disease regular hemodialysis at Pediatric Nephrology Unit, Pediatrics Intensive Care Unit of Children Hospital, and Clinical Pathology Lab, Faculty of Medicine, Zagazig University. All patients were subjected to serum hyaluronic acid (HA) measurement. Results: There is a highly significant difference between patients with AKI and CKD regarding serum HA (which is higher in patients with CKD). There is a significant relation between outcome of patients with AKI and serum hyaluronic acid. On doing pairwise comparison, the difference is significant between patients who developed CKD and those improved. Hyaluronic Acid as a Marker to Differentiate Acute Kidney Injury from Chronic Kidney Disease in Children and to Predict Chronicity for Acute Kidney Injury Section A-Research paper 974 Eur. Chem. Bull. 2023,12(Special Issue 4), 973-991 Conclusion: Serum hyaluronic acid concentrations increase in CKD and could be used as a noninvasive biomarker to predict chronicity in AKI. Keywords: Chronic kidney disease, acute kidney injury, and hyaluronic acid.