CKD children and bioimpedence Actually, healthy children, pediatric dialysis patients and renal transplant populations had got benefit from bioelectrical impedance analysis. Bioimpedence is a highly beneficial ,easy, cheap and non-invasive method for measuring total body water content, fat and fat-free mass in dialyzed and post-transplantation patients (Franz Schaefer et al., 1999). Acute and chronic changes of body composition are present in CKD Children. In infancy, uremic anorexia usually causes malnutrition and wasting. Also, if infants on forced feeding regimens, they are liable to get obesity so achievement of normal lean body mass is not clear. In dialytic childern, occult water retention usually mask wasting of fat-free mass. Dry weight assessment in a continually growing body is a challenge for the nephrologist (Elke Wühl etal.,1999). The assessment of body composition after renal transplantation, still needed as a main portion of patient carethat is mostly neglegted. Cushingoid appearance resulting from corticosteroid usage to maintain immunosuppression, so assessment of body composition is essential to distinguish between changes in body fat and those in metabolically active fat-free tissue (Reinhard et al., 1999). Applications of BIA in CKD:1. Identification of the Dry Weight The most significant cause of mortality in hemodialysis patients after diabetes is hydration status (Wabel et al. 2009). High risk of pulmonary and cardiovascular problems leads to a high correlation between mortality and overhydration in hemodialysis patients (Nescolarde et al. 2004). That is why dry weight is established as a key factor for the dialysis treatment adjustment. In hemodialys dry weight as a therapeutic target is defined as the weight of patient at the end of a session, in which removal of the maximum amount of fluid had done in the absence of antihypertensive with no induced hypotension (Charra 2007). Hypertension and cardiovascular problems can be induced if the patients are not dialyzed up to their optimal weight as that cause a permanent state of hydration (Wabel et al. 2008; Machek et al. 2008) Instead, if a final goal weight is needed for the patient after several sessions of dialysis with associted increase in the lean mass and fat resulting from good nourishment, dehydration will be developed causing intolerance of dialysis (Piccoli 2002)..Dry weight estimation depends on the ratio of ECW to TBW, the ratio of ECW and body weight or ICW to ECW (Kotanko et al. 2008).