Twenty-one hemodialysis patients were studied during 25 dialysis sessions with a dialysate sodium of 140 mEq/L and during 25 sessions with a high and variable sodium dialysate (145 mEq/L decreased to 140 mEq/L). Bicarbonate dialysate and ultrafiltration-controlled dialysis equipment were used. Neither the average interdialytic weight gain nor the predialysis and postdialysis blood pressures changed. The need for 5% saline infusions decreased from 168 + 137 ml/patient to 2 + 6 ml/patient for 25 dialyses. Use of 0.9% saline boluses remain unchanged. Fewer dialysis sessions required the use of the Trendelenburg position (p < .02) or a decrease in the transmembrane pressure (p < .05). With the use of high and variable sodium dialysate concentration, patients had less symptomatic hypotension (p < .05) and fewer symptoms of dialysis dysequilibrium, such as cramps or nausea.