The relationship between GDP in PPS (Purchasing Power Standard), and greenhouse gas emissions (in equivalent tonnes of CO₂) is an indicator of the level of eco-efficiency of an economy. The result of this relationship is expressed in equivalent tonnes of CO₂ per million euros generated in the economy. Thus the countries that present a lower relationship between the two variables, i.e. those that produce the lowest emissions into the atmosphere for every unit of wealth generated, will be the most eco-efficient, and therefore they will have more sustainable production patterns. A comparison is presented between trends in eco-efficiency in the Basque Country and that of the countries of the European Union 28.