Background: The mean platelet volume (MPV), which is a readily available indicator of platelet activation and function, is considered as a promising predictive and prognostic biomarker of cerebrovascular and cardiovascular diseases in several studies. The larger platelets tend to aggregate and produce larger amounts of adhesion molecules than small ones. Objective: To investigate the relationship between MPV levels and the glomerular filtration rate (GFR) in pediatric patients with Chronic Kidney Disease (CKD). Patients and Methods: A prospective case-control study was carried out at the Nephrology Unit in the pediatric department of Zagazig University Children Hospitals.40 children participated in study 20 of them having chronic kidney disease as a case group and a similar number of control children comparable with case group. We reviewed the medical records of patients between May 2018 and February 2019. Results: In this study, there was a positive significant correlation between MPV with Red cell Distribution Width (RDW) and creatinine and a negative correlation between MPV and eGFR in the CKD group. There was a statistically significant difference between case and control groups as regard serum creatinine, urea, and eGFR. There was a highly significant difference between the two groups regarding Hemoglobin, MPV, and RDW. There was a statistically significant difference between the two groups regarding systolic blood pressure (SBP) and diastolic blood pressure (DBP). There was a significant difference between the two studied groups as regard weight. MPV was significantly increased with the progression of CKD. Thus the lower the results of eGFR reflecting poor stage and prognosis of chronic kidney disease accompanied by higher values of MPV. Conclusion: The useful estimation of MPV provides a promising Cheap Biomarker in the monitoring of the course of progression in Chronic Kidney Diseased Children.