As it is well known, the input-output analysis is a tool of forecasts for inter-sectorial requirements, bused on the hypothesis of the independent development of the final demand. The demand is, therefore, influenced only by exterior elements connected with the change in tastes, in.the economical and techno logical progress, and by the specific targets at which the Government aims in an economic system more or less controlled . So, the matrix is, basically, a tool of economic planning. How could then input-output analysis be suitably applied to a problem of micro-economy such as the survey of the specific branch of plastics materials? Starting from an already aggregated and accepted scheme of Italian matrix, made for the year 1953, the "Chemical sector" can be divided into the various types of plastics materials; the chemical field is thus split up into two branches: the former including the whole of chemical products - plastics materials excluded - and the latter subdivided into the different productions of plastics materials. Since the branch concerning "Other manufacturing industries" is also interested in plastics materials, as a manufacturer of the same, an analogous division has also been made in this sector.