One of the main tools for the operation of the Free Trade Agreements (FTAs) are the Rules of Origin that allow exporters to be able to take advantage to the preferential tariffs. In the case of a Mexico, such rules were inserted in our legislation firstly, as a result of the North America Free Trade Agreement (NAFTA) and from there after by other trade agreements, and secondly as a tool for exempting the application of dumping duties, principally those applied to China. Mexico has undergo through a process of signing new FTA s as the Comprehensive and Progressive Trans-Pacific Partnership Treaty, as well as the modernization of NAFTA that resulted in the United States, Mexico and Canada Agreement (USMCA) and the FTA with the European Unión. The former has provided for a new rule of Origin in the automotive industry that were the core of the negotiations which turned free trade into a trade administration Trade Agreement. In this article I analyse briefly the rules of origin in such agreements.