In Bernard-Marie Koltès’ artistical life there is a remarkable and sudden stylistic gap: the passage from his old way of writing and the new one is not progressive. In the late 70’s his new pieces are absolutely different from his previous works. This article aims to show the origin of this new theatrical conception, emphasizing the significance of some biographical details. There is a traumatic moment in bmk’s biography which accounts for the radical shift both in his life point of view and in his theatre. The night of Koltès is the night which upset his whole world, marking a real turning point in his life.