In this clinical trial study 25 patients of ESRD under hemodialysis in Fateme Zahra Hospital Mehriz Yazd in 1392, by purpose to recognize the best methods of Dialysis set heparinization, is assessed and heparinated by one of three methods of heparinization(1 - 2500u heparin stat and two times 200cc N/S infusion 2 -2000u heparin stat and 1000u/h to 1hr before end of dialysis 3 -2500u heparin stat and 2500u 2hr later ) .The PTT and UREA is checkek before and after of dialysis and assessed the different in two stages.The clot measurement is evaluated by one of four degree (no clot:o - low clot:1 - moderate clot:2 - severe clot:3 )in end of dialysis.This patients must be tolerated 4 hr Dialysis and have not coagulation problems or blood transfusion from one week ago.For assessment of dialysis efficacy and coagulation condition PTT and UREA will check and compare before and after of dialysis .Coagulation scale is (no clot;no evidence of clot in dialysor,low clot:clot in 1/4 diameter of dialysor,moderate clot:clot in 1/4 to 1/2 diameter of dialysor,severe clot:clot in above of 1/2 diameter of dialysor). Assessment of clot will be reliable because the clot will observe by one person.Sampling,speed of dialysis,method of access,kind of dialysor,dialysis solution,temperature,hydration,system of dialysis machine,dialysis set ,... for whole samples is equal.