The number of kidney transplants performed per year is limited by the availability of donor organs. One novel solution to this shortage envisions "growing" new kidneys in situ via xenotransplantation of renal anlagen. We have shown that developing metanephroi transplanted into the omentum of animal hosts undergo differentiation and growth, become vascularized by blood vessels of host origin, and exhibit excretory function. Metanephroi can be stored for up to 3 days in vitro before transplantation with no impairment in growth or function postimplantation. Metanephroi can be transplanted across both concordant (rat --> mouse) and discordant/highly disparate (pig --> rodent) xenogeneic barriers. This review summarizes experimental data relating to the transplantation of developing kidneys.