The cumulative consumption of non-renewable exergy connected with the fabrication of particular products has been termed as their ecological cost. System of linear input-output equations determining the ecological costs has been formulated. The cogeneration processes have been considered using the principle of the avoided costs of fabrication of the products substituted by the by-products of the considered process. The ecological cost determined in a regional scope takes into account the ecological cost of the imported raw materials and semi-finished products. This quantities have been substituted by the economically equivalent export of own products. The deleterious effect of the rejection of waste products to the environment has been approximately determined by means of the monetary indices of harmfulness of waste products. It has been proved, that the ecological cost of human work cannot be introduced into the set of input-output equations. Exemplary calculations have been made for the products connected with the blast-furnace process. The influence of the injection of auxiliary fuels into the blast furnace on the ecological cost of pig iron has been analyzed too.