The notion of brain death has come into existence within the past thirty years along with the extraordinary advancements in medical technology and the creation of the intensive care unit. Patients who should have already passed away are being given a chance to continue living for a considerable period of time. On one hand this has become salvific in many cases, bringing back to life those people who have already lost it. On the other hand, however, this creates huge problems in such cases where individuals have suffered final and irreparable brain damage, either total or in some sections of the brain. Keeping such an individual alive is possible only by employing artificial means, but this can not go on indefinitely. Long term life maintenance of people in this state has invoked questions as to whether such individuals are dead or not, as well as doubts whether prior methods of determining death were sound. A definitive and an irretrievable damage of the brainstem has come to be called brain death or brainstem death. The author crystallizes the notions of brain death and clinical death. Clinical death is characterized by a state attained by an individual whose heart has stopped functioning, but who has not suffered brain death as yet which would make him definitely dead. Thus, brain death may occur immediately after clinical death, but it is not to be identified with clinical death. However, there exists no clear functional borderline separating life from death; and it is questionable if we have the right, or if we are at all capable or obliged to draw such a line. Thus an analysis is being made of the four principles of medical deontology which stem from religious and philosophical traditions dealing with the uniqueness and sanctity of human life, the ideas of good and evil, the right and wrong. It is normal that there has been no lack of doubt both on the medical and the ethical-religious planes. The theme of brain death, its definition and its diagnosis as the death of the entire body is linked to the issues regarding body organ transplantations. Those who are brain dead are potential organ donors and this has caused grave doubts and numerous disputes regarding the objectivity of criteria and the objectivity of those pronouncing death. The author concludes that the notion of brain death is of a very recent date so that it would not be logical to consult Orthodox Tradition or the Holy Fathers for any concrete answers regarding this matter. When organ transplantation is at issue, the Orthodox Church, going along with the popular sense, accepts organ donation both by the living and the dead donors. This might represent an indirect acceptance of brain death as being the ultimate death of a human being, since the receipt of transplants (heart, lung, liver), which are not dead as yet, presupposes the death of the donor as an individual. It is quite clear that death is not a momentary occurrence, but a procedure of a successive dying (deaths) of various organs where technology is able to intervene and by doing so slow down or prevent death from occurring. All that remains for us to do is to stand with reverence before the mystery of death and attempt, by using all available resources at our disposal, to apply all that modern technology might offer for the wellbeing of the patient, but adhering to the principles of “benefiting” and not “harming”, of freedom and justice. The attitude of respect towards the person and the life of a patient, which corresponds to the respect extended to the persons and lives of others, be it the loved ones or the ailing who go on living owing to mechanical support or organ transplants, will lead us to such practice which shall be the practice of love, justice and offering.