Over 300,000 patients who need renal replacement therapy in our country are struggling to cope with daily life restrictions and complications because of dialysis therapy. They have to spend 3 half days a week for hemodialysis therapy which accounts for 95% of all renal replacement therapies in Japan. Moreover, they also have to be afraid of many complications associated with dialysis. Although these complications mostly arise from the shortage of dialysis quantity, we have been unable to improve the hemodialysis therapy system using extracorporeal circulation. Recently, we clinically investigated long-term dialysis therapies - one was a home-dialysis system and the other a portable dialysis system. We have also developed a very small dialysis device using nanotechnology, considering an implantable artificial kidney instead of transplantation in the near future.