Xenotransplantation research is one of the most advanced in the history of surgery. It seems to be wonderful answer to the problem of shortage of organs. Yet it raises a series of medical, legal, moral, psychological and human rights questions. Among these is the possibility of new strains of infection which could trigger off a major epidemic, endangering life everywhere and causing researchers to halt and take stock of the situation. This is one of the most detailed studies available of the implications of this research for law and society. It resulted from a study conducted by the author at the invitation of the Harvard Medical Faculty where he spent some time as a Visiting Professor researching this subject with faculty members who are in the vanguard of this dramatic research.