Clinical xenotransplantation, the transplantation of cells, tissues or organs from non-humans
to humans, crosses a species barrier that has evolved over millions of years. In doing so, it
promises a great benefit to some patients, but it creates the possibility of new disease
entering the human population. The ethical issues posed by this dramatic tradeoff of
individual benefit against societal risk is the subject of this paper. These ethical issues
demand an approach different from that usually taken in the evaluation of new medical …