The purpose of the article is to present the achievements of John Stuart Mill in terms of the theory of international trade exchange. Mill was an economist, philosopher and great polymath whose work closed the traditions of the classical school and led it into the neoclassical era in the history of economy. His thought was rooted in the liberal and utilitarian theories of British classics, but it stands out as a result of confronting the abstract, model approach with observations of the effects of practical application. This methodological approach allowed Mill to achieve very interesting results, which provided valuable contribution to and further developed the theory of international trade. The paper has been written primarily on the basis of an analysis of direct sources and is an attempt to present Mill’s most interesting original thoughts regarding this subject. The subjects of the article are, in this order: the epistemological perception and principles of international trade exchange; the theory of reciprocal demand – as a continuation and elaboration of the theory by Adam Smith and David Ricardo; the theory of protection of infant industries – an original correction of the key principles of the classical school regarding free trade; the principle of compensation in theoretical and practical terms.