The paper rejects "brain death" as a new criterion, or definition, of actual death. The main theses are two: 1. Brain death as such--in any of its meanings--is not man's death and this can be proven by means of many cogent and some plausible arguments. 2. Even if the theoretical arguments against the identification of man's actual death with brain death did not demonstrate their non-identity, the opposite position would still be uncertain, at least. In view of this undeniable fact, a minimal ethical responsibility demands that we must not act, by organ retrievals, on the assumption of the identity of "brain death"--in any of its meanings--with man's actual death. We must avoid those actions which, like killing, presuppose a high degree of moral certainty concerning death, given that we cannot attain such certainty, as in the case of brain death. Thus organ and heart-explantations are found to be unethical. A newly thought out notion of biological death of the human organism as a whole ("clinical death" as irreversible cessation of all vital bodily functions, in particular of cardiopulmonary and cerebral functions) is proposed as theoretically best founded and ethically safest medical criterion of death.