This prospective study was designed to evaluate hypotension in a group of 21 end stage renal disease patients (ESRD) on hemodialysis, with syntomatic low blood pressure. The arterial blood pressure was recorded at 4 consecutive dialysis sessions, two at 35 degrees C and two at 37 degrees C dialysate temperature. In both situations, systolic and diastolic pressures, measured during dialysis, were different from the pre-dialysis value, with progressive lowering up to the end of the procedure. Cold dialysis did not protect from lowering the blood pressure in an amount similar to that occurring at 37 degrees C.