In a clinical trial (cross over method) 30 hemodialysis' patients will be study during two hemodialysis sessions by High Flux with Low Flux filters to compare the effects of these filters in the clearance of articles, Level of Electrolytes and in Patient's Comfort. Including criteria are: fistula or arteriovenous graft vascular access; three weekly dialysis sessions; four hours per dialysis session; coping bearing in dialysis sessions; at least six months of dialysis experience; consciousness and the ability to fully participate in the project; no history of heart disease, pulmonary disease and other acute disease; need to less than three liters of ultrafiltration and hemoglobin greater than 8 mg/dl. The incidence of complications in hemodialysis (blood pressure changes, nausea, vomiting, itching, muscle aches and headaches) with a list of Czech research and questionnaires are recorded. During the second session, sampling of the arterial line before and after dialysis For Evaluation amounts of sodium, potassium, phosphorus, urea and creatinine are done. During the second stage, the same 30 patients are done hemodialysis with filter High Flux two session. All procedures and measurements is the same . Hemodialysis procedure has proved in two steps. If patients with severe hypotension, severe complications of hemodialysis, no patient discontinued dialysis and cause allergic reactions, patients are excluded. Results between the two phases, the rate of clearance of particles , electrolyte and complications of hemodialysis between the two filters, are compared.