Background: New controversies have raised on brain death (BD) diagnosis when lesions are localized in the posterior fossa. Objective: To discuss the particularities of diagnosis BD in patients with posterior fossa lesions. Material and Methods. The author made a systematic review of literature on this topic. Results and Conclusions: A supratentorial brain lesion usually produces a rostrocaudal transtentorial brain herniation, resulting in forebrain and brainstem loss of function. In secondary brain lesions [i.e., cerebral hypoxia], the brainstem is also affected like the forebrain. Nevertheless, some cases complaining posterior fossa lesions [i.e., basilar artery thrombotic infarcts, or hemorrhages of the brainstem and/or cerebellum] may retain intracranial blood flow and EEG activity. In this article I discuss that if a posterior fossa lesion does not produce an enormous increment of intracranial pressure, a complete intracranial circulatory arrest does not occur, explaining the preservation of EEG activity, evoked potentials, and autonomic function. I also address Jahi McMath, who was declared braindead, but ancillary tests, performed 9 months after initial brain insult, showed conservation of intracranial structures, EEG activity, and autonomic reactivity to “Mother Talks” stimulus, rejecting the diagnosis of BD. Jahi McMath’s MRI study demonstrated a huge lesion in the pons. Some authors have argued that in patients with primary brainstem lesions it might be possible to find a in some cases partial recover of consciousness, even fulfilling clinical BD criteria. This was the case in Jahi McMath.