Due to the increased number of cases of chronic renal failure in children this search is done to study the efficacy of haemodialysis as a replacement therapy in these cases .In broad terms, the process of hemodialysis involves bidirectional movement of molecules across an artificial semipermeable membrane outside of the body.Dialysis is dependent on the concentration of toxic solutes accumulating in renal failure. Urea has been successfully used as a toxic solute marker to define adequate dialysis therapy through urea kinetic models.Prescribing hemodialysis is affected by many components. These include estimation of dry weight which may be achieved by clinical assessment, biochemical markers, inferior vena cava diameter, bioelectric impedance, or noninvasive blood volume monitors.