In the modern world, a human being comes across the double absolute priority given to the values of medical ethics. On the one hand, moral ideals are metaphysical by nature. On the other hand, a human being treats ethical standards of medical ethics pragmatically. In this aspect, the key players of the ancient world who developed the metaphysical basics of medical ethics were especially important. The study is aimed at determining the contribution of ancient thinkers into development of fundamental basics of medical ethics. The works of ancient thinkers were taken as materials for the study. The study methods are represented by system analysis, dialectic method, phenomenological and hermeneutical approaches that enable to interpret the ideas of thinkers in relation to creating the basics of medical ethics. It has been established during the study that thinking based on the integration of rational, empirical and metaphysical principles has been developed in the ancient world. Metaphysical provisions of Plato and Aristotle manifested through the works of Galen make it is possible to conclude on eclectic philosophical views of Claudius Galen. Eclecticism is not just about plain borrowing of ideas, but about new fusion of physics, logics, and metaphysics in relation to understanding human health and disease. It can be stated that the first stage of nature cognition (natural philosophy) is the most important stage of developing sense-making basics of medical ethics. This period turns into a starting point for the emerging basics of fused humanitarian and natural science- based knowledge and formation of medical ethics principles.