This research is a clinical trial which will be performed in Latin square and single-blind method. The purpose of this research is to determine the combined effect of sodium and ultrafiltration profiles on some of the common complications during hemodialysis. The samples are hemodialysis patients in Panje Azar Hospital of Gorgan, Iran, who had hypotension for more than three sessions during last month. Other inclusion criteria are age of 18-75, hemodialysis for more than three months and three times a week with a solution of sodium bicarbonate. The patients have systolic blood pressure <100 mm Hg before starting dialysis. Patients with complications which would be studied in this project (cramps, nausea, vomiting and headache) and patients who recieve analgesic, anti-hypertensive and anti-spasmodic are not included. The samples, 44 patients, are selected by accessible sampling method, and randomly allocated to four groups of 11 members. In each of the groups, one specific protocol for hemodialysis is performed. 1: Linear sodium dialysate and constant ultrafiltration. 2: Constant sodium dialysate and gradient ultrafiltration. 3: Linear sodium dialysate and gradient ultrafiltration. 4 (standard hemodialysis): Constant sodium dialysate and constant ultrafiltration. In every session, blood pressure is monitored five times. Any muscle cramps, nausea, vomiting and headache are recorded. GAMRO AK96 hemodialysis machine are used for all samples.