Abstract: This article examines the main vector of development of ontologies in European philosophy of the XX century. The subject of this research is the concept of “poetic ontologies”, proposed by Alan Badiou applicable to fundamental in their essence projects of Martin Heidegger and Gilles Deleuze, An attempt is made to explicate the specific conceptual meaning of the poetic in the referred projects by revealing its differences from poetry in a narrow sense of versification, and its correspondence with the fact that in Deleuze’s texts it received a name of schizophrenic language. Alongside the general scientific methods of description, analysis and synthesis, the author also used the hermeneutic method and comparative analysis. Application of the concept of “poetic ontologies” in respect to the projects of M. Heidegger and G. Deleuze, found its substantiation and legitimacy in the course of this research. The main conclusion consists in elucidation of the constructive link of the poetic with the certain interpretation of existence, known as nature and opening a prospect for the nonclassical forms of reasoning.