The risk of post-operative liver failure is the central problem in the field of liver resection and transplantation. This is principally due to the "small-for-size syndrome", an excessive and destructive portal flow through a remnant liver that is too small, which becomes functionally insufficient. Indeed, there is no efficient and safe method that can be used to manage a greatly reduced remnant liver size. We postulated that adjustable portal vein banding, to control the portal venous flow and act as a progressively opening "dam", in proportion to the initial remnant liver weight and its natural growth, could avoid post-operative liver failure of an extremely small remnant liver, by preventing small-for-size syndrome and stimulating liver regeneration, thus, revolutionizing the "liver world". It may become possible to totally overcome the dramatic worldwide shortage in liver grafts, by transplanting several adult patients from each multiple spliced cadaveric liver, or by ethically acceptable living donation of an extremely small graft. Furthermore, it could make resectable and maybe cure thousands of patients suffering of liver metastases actually defined "un-resectable", through the safe use of extreme hepatectomy.