The systemic physiologic changes that occur during and after brain death affect all organs suitable for transplantation. Major changes occur in the cardiovascular, pulmonary, endocrine, and immunological systems, and, if untreated may soon result in cardiovascular collapse and somatic death. Understanding these complex physiologic changes is mandatory for developing effective strategies for donor resuscitation and management in such a way that the functional integrity of potentially transplantable organs is maintained. This review elucidates these physiological changes and their consequences, and based on these consequences the rationale behind current medical management of brain-dead organ donors is discussed.