In this paper, we argue that, contrary to the view held by most philosophers of mathematics, Bourbaki's technical conception of mathematical structuralism is relevant to philosophy of mathematics. In fact, we believe that Bourbaki has captured the core of any mathematical structuralism. * The author gratefully acknowledge the financial support of the SSHRC of Canada while this work was done. This paper is part of a larger project on Bourbaki and structuralism which would not have seen the day without Michael Makkai's influence and generosity. I want to thank him for the numerous discussions we had on the subject. I also want to thank Alberto Perruzzi and Silvano Zipoli for inviting me to present this work at the conference on Bourbaki, mother structures and category theory.