This chapter outlines the two means of determining biological death: one is cardiopulmonary, and the other neurological. It provides support for the continued use of the brain death concept based on operational usefulness and its moral rightness in that it can provide good in the absence of harm and, for most, in the absence of offense to intuition or moral sense. Brain death is the irreversible cessation of whole-brain function, which would be followed by the cessation of cardiopulmonary function without the institution of artificial measures. Recognition of the vegetative state (VS) entails a clinical diagnosis. The VS is likely to be permanent 12 months after traumatic brain injury and 3 months after nontraumatic injury in children. Minimally conscious state (MCS) is considered by some to be a neurological state whose recognition allows special legal and moral consideration. The interpretation of "minimal" becomes "hardly different from vegetative".