Past, present, and future developments of haemopurification systems are reviewed with respect to their biocompatibility and functional capability. The history of the polymethylmethacrylate (PMMA) membrane is introduced, along with the modifications aimed at removing beta 2-microglobulin (beta 2-M). A highly permeable PMMA membrane (BK) has the capability to adsorb beta 2-M. We have succeeded in finding material, thought to be beta 2-M, in transmission electron-microscopy of the membrane perfused with plasma from haemodialysis patients. As examples of the future development of haemopurification systems to remove targeted substances more specifically and efficiently, we consider hybridised bioartificial kidney containing proximal renal tubular cells fixed on collagen hollow fibre for degradation of beta 2-M to aminoacids, and an artificial reticuloendothelial system with polymyxin B immobilised fibre for removing endotoxin in blood. Targeting and specific removal with prepared biocompatible materials will open the way to the development of the second generation systems and close collaboration between medicine and industry is essential for realising these goals.