Abstract : This thesis examines how the Oulipian Jacques Roubaud, while rewriting texts and motifs from Middle Ages, also recaptures an ancient practice of literature. Indeed, throughout his work, Jacques Roubaud acknowledges medieval literature as an inspirational field. Not only does he publish, as a true scholar, several essays about troubadours and Arthurian romances, but also considers texts and writers of Middle Ages as examples to be followed for his own material. He seems to recognise himself in the medieval conception of literature, in which originality is not a matter of newness but consists in dealing with what has already been told. Writing is always about rewriting, adapting and passing old tales on, in a medieval word, writing is about "translatio". By reconstructing the old library that Jacques Roubaud paces, this study therefore analyses the numerous mechanisms of rewriting in the light of medieval poetic.