Transplantation is a life-saving procedure, but the price is the lifelong use of immune-suppressing drugs. Organ rejection after transplantation occurs because the immune system scans for foreign cells. If the immune system in the transplant recipient weren't heavily suppressed, it would attack cells in the transplanted organ, leading to rejection. This new approach to kidney transplantation began in the usual way, with surgery followed by immune-suppressing drugs, which were needed to prevent organ rejection while the team completed the next step. After the transplant, the kidney recipient received multiple small doses of radiation targeted to the immune system combined with a drug to reduce the number of cells capable of an immune attack. The team then injected blood stem cells from the kidney donor into the recipient. The stem cells made their way to the recipient's bone marrow where they produced new blood and immune cells that mixed with those of the recipient. After this procedure, the recipient's immune cells recognize the donor's organ as friend rather than foe. This study represents the direction in which transplantation will move in the future. In the past, the goal was to have a transplanted organ function in the recipient.