Objective : Ion transport system plays an important role in epilepsy . Erythrocyte membrane Na+,K+ ATPase was chosen to investigate the transport alteration in epilepsy . The aim of this work is to study the activity of Na+,K+ ATPase enzyme for epileptic patients with and without taking medications and the effect of Carbamazepine in enzyme activity . Subject : One hundred and three subjects were enrolled in this study and subdivided into three groups . The first included 41 control subject with mean age of ( 30 ± 6 ) years . The second group involved 31 epileptic patients without taking medication (untreated) with mean age of ( 26 ± 5) years .The subjects of third group were 31 treated epileptic patients with Carbamazepine in a mean age of ( 29 ± 7) years Methods : For those patients , ion transport alteration was evaluated by measuring the Erythrocyte membrane Na+,K+ ATPase enzyme activity and Michaelis -Menten kinetic parameters ( Km and Vmax) . The serum electrolyte ( Calcium , Inorganic phosphate , Magnesium , Sodium and Potassium) were estimated . Other biochemical parameters ; Blood sugar ,urea ,serum creatinine , GOT , GPT , alkaline phosphatase bilirubine and albumin were also estimated for the three groups of subjects to exclude those having diabetic , renal and liver disease .