Over the last 20 years, a number of methods and solutions have been developed to preserve donor organs for transplantation. Collins et al first introduced the simple cold-storage technique to store and transport kidneys up to 30 hours. The development of the University of Wisconsin cold-storage solution (UW-CSS) in 1986 improved organ preservation and resulted in a better understanding in preservation related injury. Since its introduction, several UW-CSS-derived solutions have been tested, and important components for hypothermic preservation were identified. Pathophysiologic mechanisms in static hypothermic preserved organs are discussed, including hypothermia-induced cell swelling, compromised membrane function, adenosine triphosphate usage, cellular acidosis, and prevention of precursor formation of reactive oxygen species. Counteracting these pathophysiologic mechanisms can be divided into components acting by two protective principles. The first is to create a physical environment, minimizing cellular and interstitial edema formation. The second mechanism involves biochemically active components that ideally enter the cell and remain effective during reperfusion. Some preservation solutions currently in use are discussed on the basis of these two protective mechanisms. In respect of these principles in preservation, new solutions in preservation are discussed. Although cold-storage solutions improved organ viability, maintaining or even improving organ quality during preservation remains an important goal. Future advances in preservation might be found in donor pretreatment, cytoprotection, or the use of dynamic preservation systems. © 2002 Elsevier Science (USA). All rights reserved.