Methods:This study aimed to evaluate the effect of cool dialysis in hemodialysis patients and is done in three steps.The study population consisted of 30 patients with end-stage renal failure in the age range 15 to 80 years,that they are at least three months before to become permanent hemodialysis.In the first phase, patients initially will be hemodialysis for three sessions (one week)with dialysate at 37Cº.Before and after each session of dialysis , oral temperature is measured and will be recorded.Systolic and diastolic blood pressure and pulse rate will be measured at the bigining of dialysis, first, second and third hours during dialysis and immediately after dialysis in each session then will be recorded.Number of hypotension episode with signs such as muscle cramps, nausea and vomiting, and interventions to improve it, such as normal saline administration, Trendelenburg position, using hyper tonic solution, reduction of ultrafiltration and slow down the device will be recorded in the check List.At the end of the third session, the comfort of patients will be measured by Visual comfort criteria . To assess the adequacy of dialysis, blood samples will be collected before and after the third session of hemodialysis.In the second phase of the study, the patients will be hemodialysis by a solution of 36 C º for three sessions (one week).The process is exactly the same as the first stage. The only difference is that in addition to monitoring vital signs if patients have feeling cold or shivering must be register in check list.The third phase is quite similar to the second stage, but dialysate temperature is 35 C º.At the end of the study, the patients are asked what temperature they prefer dialysis.