The first part of this article is an analysis of the historical and philosophical evolution of the concept of human person, from antiquity to present times, including an outline of its major developments. The second part deals critically with reductionist and empiricist positions -particularly Engelhardt's and of utilitarianism- exposing some of its practical implications in the realm of Bioethics. Finally the author concludes with an enunciation of what would constitute a conceptual basis for the ontological foundation of Personal Bioethics derived from the initial framework of intuitive ideas first outlined by Sgreccia in the eighties.