This edition presents eight treatises by Galen (129/131–210/217), an outstanding Roman physician and philosopher of the 2nd–3rd centuries, the creator of a theoretical and practical system that became the basis for the development of medicine and natural science in general until the scientific discoveries of the 17th century V. The published translations are equipped with an extensive introductory article, comments and notes by the historian of science Dmitry Alekseevich Balalykin and bibliography. The methodology proposed in the publication allows us to show the mutual influence of natural philosophy and medicine. The works collected in the publication are a typical example of the connection between Galen’s general theoretical, natural philosophical views and his practical activities as a doctor. Published works demonstrate excellent mastery of the empirical method and skills of synthetic thinking, built on the principles of rational medicine. All this allows us to comprehensively comprehend the historical significance of Galenism.