This work deals with the status of contradictions in the philosophies of Gilles Deleuze and Alain Badiou. Within this framework, we did not pretend to introduce an overall interpretation of the ways these thinkers understand contradictions. Our purpose was only to focus on several issues like the relation between negation and contradiction, and to discuss their different approaches to those issues. Therefore, we have limited ourselves only to some of those philosophers' writings. This work also contains a technical-logical part, and a proper philosophical discussion.