Reduced red blood cell (RBC) survival due to oxidative damage is one of the causes of anemia in patients under long-term hemodialysis. Recently, it has been shown that vitamin E-bonded dialyzer membrane is able to reduce the oxidative stress during hemodialysis. In humans, creatine content in RBC is used to measure RBC life span and erythropoietic capacity, since it rapidly declines as the RBCs become old. Therefore this study aimed to elucidate the effect of vitamin E-bonded dialyzer membrane on RBC life span by measuring creatine content in RBC.