The authors suggest a definition of the apodictic method that can be applied to the history of medicine and reveal its development in the works of Hippocrates, Aristotle, and Galen. The apodictic method of proof in medicine is anatomical dissections, the rational doctrine of general pathology and clinical systematics. The particular approach to using this method of rigorous proof in the works of ancient authors allows us to distinguish three stages in the development of ancient medicine’s methodology