The article focuses on Milton Friedman's contribution to the economic science. Milton Friedman belongs to the outstanding economists of the past century; he was one of the founders of the Chicago School, the symbol of monetarism and the leader of the contemporary economic liberalism. Milton Friedman considered free market as the most efficient form for the economy. His contribution to the economic science development is extraordinary. It concerns not only the pure theory and methodology of economic analysis but also empirical analysis, economic policy and the area of basic issues on the comparative economic systems. The core of Friedman's input to the pure economic theory is the first of all his monetary theory - the money-demand and the money-supply conceptions, inflation, as well as the mutual relations between inflation and unemployment.