ObjectiveTo evaluate whether current criteria for the diagnosis of brain death fulfill the requirement for the “irreversible cessation of all functions of the entire brain, including the brainstem.”Data SourcesClinical, philosophical, legal, and public policy literature on the subject of brain death.Data Extraction/SynthesisWe advance four arguments to support the view that patients who meet the current clinical criteria for brain death do not necessarily have the irreversible loss of all brain function. First, many clinically brain-dead patients maintain hypothalamic-endocrine function. Second, many maintain cerebral electrical activity. Third, some retain evidence of environmental responsiveness. Fourth, the brain is physiologically defined as the central nervous system, and many clinically brain-dead patients retain central nervous system activity in the form of spinal reflexes. We explore options for resolving these inconsistencies between the conceptual definition and the clinical criteria used to make the diagnosis of brain death.ConclusionsBrain death is a valid conception of death because it signifies the permanent loss of consciousness. Brain death criteria should therefore be based on the diagnosis of the permanent loss of consciousness rather than that of the loss of vegetative brain functions. Revision of our current “whole brain” definition of brain death to a “higher brain” standard should be considered.