Ischemic injury to the renal allograft, prior to implantation, is an important cause of delayed graft function. With improved understanding of the pathophysiological mechanisms involved, strategies have been devised to minimize ischemic injury during preservation ex vivo. It is clear that reducing the warm ischemic time, flushing the kidney with hypothermic solution containing cell-impermeant compounds, and maintaining the organ at low temperature ex vivo have increased the duration that the kidney can be preserved. The effectiveness of a number of other components of preservation solutions, as well as the relative merits of continuous perfusion of the organ ex vivo, is more controversial. In this chapter, we review the mechanistic features of ischemic acute renal failure and discuss various preservation strategies and their success in the context of these basic principles of ischemic pathophysiology.