Xenotransplantation is the transplantation of organs and cells from one species to another: it has enormous potential to increase the supply of organs and tissues to alleviate human disease. Recent scientific progress has eliminated the obstacle of hyperacute rejection, which is the massive destruction of the transplanted organ within 24 h. Despite this progress and the tremendous clinical potential, a number of ethical issues require careful consideration. These issues involve the human recipients, source animals, biotechnology companies and ultimately, the general public. One of the greatest concerns is the potential risk that an infectious agent will be transferred with the organ to the recipient, from whom it may spread, leading to a possible epidemic. However, there is no current evidence that porcine endogenous retrovirus, which is the agent of greatest concern, will be pathogenic. Using modern biotechnology, it may be possible to generate pigs that are free of this virus in the near future. Addressing these issues deliberately and in a scientific manner, with public involvement and education, will result in a greater understanding of the risks and benefits of xenotransplantation. This knowledge can then be utilised to fulfil the increasing demand for transplantable organs, with minimal risk.