Haemodialysed patients are exposed to nearly 400 litres of dialysis water weekly. The bacterial contamination of treated dialysate and water induces acute pyrogenic reactions or chronic damage and cytokine activation. The aim of this study was to value the microbiological parameters of dialysis water and dialysate of our monitors by bacterial culture (measured as colony forming units [CFU]) of water samples at 37 degrees C after 48 hours, at 22 degrees C after 72 hours and after seven days, and by measuring endotoxin levels (endotoxin units [EU]). In our centre, there are 16 monitors (6 monitors use sterile dialysate fluid and 10 monitors use non sterile dialysate fluid). The chemicals used for disinfection are chlorine and paracetic acid. Water samples were taken under sterile procedures every three months for a year. No bacteria were found in the samples of water of the dialysis ring; EU were lower than the limit value of 0.25 EU/ml fixed by the European Pharmacopoeia. The concentration of CFU and EU of the dialysate, taken from monitors with a sterile bag, were lower than those of other monitors (p < 0.05 t Student test). However, the levels of CFU/ml and EU/ml of dialysate samples, taken from monitors with a non-sterile bag, were lower than the guideline value of the European Pharmacopoeia (v.n. CFU < 50 CFU/ml and EU < 0.05 EU/ml). Frequent examination of CFU and EU is essential to reduce the damage caused by the use of contaminated water, therefore the goal of future dialytic techniques will be the use of "sterile dialysate".