Background: Cardiac surgery with use of cardiopulmonary bypass (CPB) is associated with the production of both proinflammatory and anti-inflammatory cytokines as a result of systemic inflammatory activation leading to an acute phase response with sepsis-like symptoms during postoperative recovery arteriovenous modified ultrafiltration effective method to reduce total body water and improves postoperative homodynamic and haemostatic functions.Objective: Our study undertaken to assess the effect of modified ultrafiltration on the postoperative clinical outcome, and its effect on the clearance of the proinfilammatory mediators in pediatric Cardiac surgery .Methods : Ninety children were divided into two groups control without modified ultrafiltration (n = 30) and test group with modified ultrafiltration (n = 60) the tumor necrosis factor (TNF), Interleukin 1 (IL 1), interleukin 6 (IL 6) , and interleukin 8 (IL 8) were measured through three samples first sample T1 was withdrawn at the induction of anesthesia , second sample T2 was withdrawn after the cross clamp at the time of rewarming ), The third one was after completion of the operation in the control group or after completion of Modified ultrafiltration MUF group (T3 ). Then these samples were separated by centrfusion and the plasma was kept in (-70 C) until further measurement of the cytokines .Results: Good postoperative clinical outcome with MUF group . For the cytokines TNF , IL-1 , IL-6 and IL-8 had statistical difference in comparison with the control group with P value in T3 0.28, 0.023,0.019 and 0.020 respectively. Conclusion : Modified ultrafiltration MUF is a safe technique and has beneficial effect on the control of the body water improve the clinical outcome & decrease the levels of the cytokines . This needs for further investigations