Chronic renal failure is responsible for a mortality rate in its sufferers that can be as much as 100-times greater than that for their corresponding age range. On-line haemodiafiltration has been shown to be effective in reducing the mortality rate in dialysis patients by increasing the connective movement of medium to high molecular weight uraemic molecules. As a result, we have been investigating which population groups gain the greatest benefit from this technique and how to improve it in order to achieve the highest efficacy with lowest cost.