Once pig organs can be transplanted into humans, transplantation will move into a new era. There will be unlimited access to undamaged organs, and cells for transplantation and, eventually, donation from deceased or live human beings will become obsolete. Furthermore, it will be possible to alleviate graft rejection, at least in part, by genetic modification of the source animal. Currently, there are three major obstacles to performing transplantations from pig to man: a powerful immune barrier, a potential risk of transmitting microorganisms, particularly endogenous retrovirus, and ethical issues related to the future recipients and to society at large. This article will first discuss the ongoing work with regards to overcoming the current obstacles. Also, the many potential advantages of using pig organs will be discussed in some detail. Furthermore, lessons learned from attempts at transplanting porcine cells to patients will be reviewed.