The aim of xenotransplantation is to allow the transplantation of animal organs or cells to humans. This approach would immediately eliminate the human organ shortage that is responsible for a significant mortality of patients on the waiting list for transplantation of organs. The immune differences between pig and human induce an immediate rejection of porcine tissues by humans. This rejection has recently been partially controlled by genetic engineering of pigs, the use of new immunosuppressive drugs and encapsulation of isolated cells. However, due to the risk of transmission of animal infectious agents to humans, the WHO recommends that clinical application of xenotransplantation only takes place if adequate regulations are in place.