The recent evolution of the international trade has been characterized, among others factors, by an increasing supplying of intermediate inputs in the international markets. In this article these firm´s decisions are analyzed, comparing the characteristics of size, productivity, age, intensity of capital, composition of manpower, innovating effort, costs, participation of foreign capital between the companies that make international outsourcing and those that do not do it. In order to organize the empirical analysis we take as reference the model of Antràs and Helpman (2004) that predicts the companies with greater productivity they select themselves when taking the decision to do international outsourcing. The article offers empirical evidence that confirms this prediction from a sample of Spanish industrial companies of the Encuesta sobre Estrategias Empresariales.