Brain death is defined as the irreversible loss of all brain functions, including the brainstem. The diagnosis of brain death allows organ donation or withdrawal of support. Therefore the exact criteria for the diagnosis of brain death must be determined. In the Croatian Act on Transplantation, repeated neurologic examination must show loss of brainstem reflexes, and one confirmation test must be done. Several tests are available, showing the cessation of brain or brainstem activity, or confirming the cerebral circulatory arrest. Bedside evaluation is possible through electroencephysiologic and neurosonologic tests. Conventional or digital subtraction angiography is done in radiology suite, and isotope angiography and technetium-99m hexamet...