Introduction: Fluid overload (FO) significantly increases mortality in critically ill children. While continuous renal replacement therapy (CRRT) is key for managing FO, optimizing the net ultrafiltration rate (NUFR) remains challenging. Objective: To assess the impact of initial FO, body weight (BW), and capillary leak index (CLI) on NUFR and fluid balance (FB) in pediatric patients receiving CRRT. Methods: This single-center retrospective study (Jan 2012-Oct 2023) included 220 pediatric CRRT patients. Exclusion criteria were: expected death within 24 hours, CRRT duration