The margin squeeze is anticompetitive conduct that has aroused great interest in the European Community framework, which, what is intended with the completion of this article is to explain what these practices, the degree of damage to the market and the legal framework sanctioning this behavior. Also, being an essential element in the prevention and punishment later in a margin squeeze, prevailing regulation will be explained within the European telecommunications sector, a sector in which there have been more strongly anti-competitive practices alter the free play of supply and demand and important subject of judicial rulings in Europe. Palabras Claves: Compresion de Margenes, Regulacion Economica, Agencias Nacionales de Regulacion, Derecho de la Competencia, Practicas Anticompetitivas.