Sustainability has emerged not only as a global concept, but also as a principle and goal which includes a set of values. In despite of the international acceptance of the concept, there is a long path to be transited in order to establish a real consensus about its meaning and applicability. The conceptual application of sustainability to Bioethics is more than a proposal about the extension of the topics that traditionally have been adjudicated to this new “discipline”. The text attempts to assess the rationale implied in Bioethics questioning the disciplinary and inter-disciplinary approaches of its internal epistemology. This evaluation will take into consideration the actual frameworks developed from ecology and earth system analysis. The main thesis to be sustained is that, in order to gain theoretical sustainability, Bioethics would need to adapt itself to a transdisciplinary approach. Following this suggestion, Bioethics will be able to face the actual requirements of a future society.