The distribution of fault systems in the axial zone of the eastern Pyrenees between the Cerdagne and Ampurdan-Roussillon basins (France) is described. Four fault systems form a network; the trends are more or less east-west, northwest-southeast, northeast-southwest, and north-south. Many of these faults also affect the post-Hercynian cover, including the Eocene. They range in age from late Hercynian to late Tertiary. The late Tertiary played a determining role in the structure of this part of the Pyrenees.