For 3 years starting in April 1989, in a 17-station, in-centre haemodialysis unit at the Toronto Western Hospital, re-use of dialysers was performed using the Renatron-2 Dialyser Reprocessing System with peracetic acid as a sterilant. During this period 40,234 treatments were carried out and dialysers were used an average of 4.2 times. Net savings, after taking into account the total costs of re-use, averaged Can $309,000,000 per year. There were no deaths and no discernible morbidity attributable to the practice of re-use. We conclude that dialyzer re-use is an effective way to reduce the costs of haemodialysis and is entirely safe providing that it is carried out properly.