Brain death is defined as the condition of irreversibly lost central nervous system functions, the inability to breathe spontaneously and maintain homeostasis, but with functional heartbeat. Situation like that represents the real border between life and death. Clinically and legally, brain death is equal to patients's death. That is why it is necessary to set up a brain death diagnosis to make space for potential organ and tissue transplantation. The largest number of transplant organs is obtained from patients in the condition of brain death, and Croatia is at the top of the world by the number of donated organs and the success of transplantation per million inhabitants. Thanks to the improvement of modern technology, it is possible to maintain breathing, delay heart failure and circulation for several hours or even days. Although the brain is irreversibly damaged, it is possible to maintain the function of whole organic systems. Brain death diagnosis is set by extensive clinical trials and is confirmed by objective tests. CT angiography has been in the focus of this work because of its advantages, which I hope will in the future play a central role in diagnosing the death of the brain. The main goal of the work was to clarify the concerns about the concept of brain death, to consider the mechanism of occurrence or pathophysiology, to present diagnostic procedures and thus to promote the role of radiology throughout the process. Radiology, as a medical specialty, plays an important role in numerous diagnostic and therapeutic procedures.