In hemodialysis therapy, the contact between blood and the hemodialysis filter induces biological reactions such as activation of the complement system, blood cell components, and the coagulation system. Since the 1960s, efforts have been made to develop dialysis membranes with excellent biocompatibility to minimize these reactions. To date, various membranes have been developed, including cellulose-based regenerated cellulose (RC) membranes, and synthetic polymer-based membranes such as polyacrylonitrile (PAN), poly(methyl)methacrylate (PMMA), ethylene vinyl alcohol copolymer (EVAL), polysulfone (PSf), polyethersulfone (PES), and polyester polymer alloy (PEPA) membranes. Biocompatibility varies depending on the membrane material. Furthermore, not only the material itself but also factors such as the membrane's hydrophobicity, surface roughness, sterilization method, surface charge, and inner diameter of the hollow fibers affect biocompatibility. Therefore, when selecting a hemodialysis filter, it is necessary to pay attention not only to solute permeability and water permeability but also to biocompatibility. Presentation: Symposium