The kidneys maintain the body's homeostasis by removing water and waste products continuously and efficiently. The ideal dialytic treatment should emulate the functions of the kidney. Of the dialysis treatments currently available for chronic renal failure, the only continuous ones are continuous ambulatory and continuous cyclic peritoneal dialysis; however, the efficiency of peritoneal dialysis is limited by the nature of the peritoneal membrane. Extracorporeal dialysis is markedly more efficient than peritoneal dialysis, but is performed intermittently (usually 3 times/week) with large fluctuations of body fluid volumes and concentrations of various solutes and electrolytes. These fluctuations cause intercompartmental disequilibrium during dialysis, induce intradialytic and interdialytic symptoms, and create difficulties in controlling blood pressure. Daily dialysis is both frequent and efficient and therefore seems to be superior to any other form of renal replacement therapy.