The development of hemodialysis from an experimental concept to a routine medical therapy is closely related to research, manufacturing and availability of dialysis membranes. Collodion, a cellulose-trinitrate derivative, was the first polymer to be used as an artificial membrane and played a central role in further investigations and applications. Basic studies on the mechanism of solute transport through membranes, like diffusion, were done by A. Fick and T. Graham using collodion as a membrane material. In vivo dialysis in animals and humans was performed with collodion by J. Abel in the USA and G. Haas in Germany. Cellophane and Cuprophan membranes replaced collodion later, because of their better performance and mechanical stability. However, due to its alleged lack of hemocompatibility, membranes made from unmodified cellulose lost their market share. They have been replaced by modified cellulosic and synthetic dialysis membranes which show a better hemocompatibility than unmodified cellulose membranes. Most of the new membrane materials are also available in high-flux modifications and for this reason suitable as well for more effective therapy modes, such as hemodiafiltration and hemofiltration. The success of hemodialysis as a routine therapy is also the success of membrane development, because both, a reproducible membrane production and an unlimited availability of dialysis membranes have increased the number of dialyzed patients to about 1 million patients worldwide in 1999.