Xenotransplantation (XTx) offers a possible solution to the severe shortage of organs for transplantation, but it will raise new legal questions. There are currently no legal impediments to XTx in the United States nor do animals possess common law or constitutional rights that would prevent it. The law remains indefinite regarding what constitutes a human being, allowing the possibility that legal arguments will be raised regarding the legal status of transgenic animals expressing human tissues or cells. As successful XTx will eliminate the organ shortage, Congress or state legislatures will have to reconsider the need for the current centralized system of allocation and distribution of organs, for this could be replaced by a commercial system based on market forces. The most significant legal issue relating to XTx is probably the potential threat to the public health and safety through the transmission of an infectious disease. The Public Health Service has recently issued draft guidelines which make recommendations about how XTx procedures might be performed. These guidelines currently have no legal authority but offer insight into how XTx might be regulated if it becomes a clinical reality. Existing federal laws, however, empower federal agencies to regulate XTx, in part because of the potential risk to the public health. Additionally, tort liability will impose legal pressure on transplant centers to minimize the level of risk that the general public might face. The most difficult questions facing legislatures and the Public Health Service may well prove to be those raised by the behavior of individual patients or their social contacts who do not comply with the guidelines/regulations relating to long-term monitoring for infectious complications. © Munksgaard, Copenhagen.