The maintenance of life of patients with chronic renal insufficiency has been theoretically possible since the development of an experimental dialyzer by Abel, Rowntree, and Turner (1) in 1913 and has been practically possible since the development of the rotating drum dialyzer by Kolff (2) 20 years ago. Early attempts to treat chronic uremic patients by repeated hemodialysis were generally unsuccessful because of the limited number of blood vessel cannulation sites. It was not until a practical method of permanent cannulation was developed by Quinton, Dillard, and Scribner (3) in 1960 that the problem was largely solved. Since then it