We define the notion of the Dade group of a fusion system and show that some of the gluing and detection results for Dade groups of finite p-groups due to Bouc and Thévenaz in [S. Bouc and J. Thévenaz. Gluing torsion endo-permutation modules. (Preprint.)], [S. Bouc and J. Thévenaz. A sectional characterization of the Dade group. J. Group Theory 11 (2008), 155–183.] extend to Dade groups of fusion systems.