This research investigate the concept of disposedness (Befindlichkeit) in Martin Heidegger in relationship with the thoughts of Saint Augustine and Aristotle. For achieve this goal we analyze the works of the German philosopher with emphasis on his writings from the 1920s to his magnum opus Being and Time (1927), indicating his interpretations of the Greek philosopher and the bishop of Hippo. The choices of Augustine and Aristotle are justified because, as highlighted by interpreters of Heidegger such as Franco Volpi, Otto Pöggeler and Theodore Kisiel, these two philosophers were relevants for the elaboration of the fundamental ontology and the entire Martin Heidegger s thought. The disposedness is the ontological foundation that opens the Dasein (being-there) to the world and reciprocally the world to Dasein. It structures, together with understanding and discourse, the meanings of the things that come to meet this being-in-the-world bringing the possibilities of becoming in its finite existence. Disposedness is therefore, for Heidegger, crucial for the meaning of being. Our goal is to indicate that Augustine and Aristotle were central to the concept of disposedness in Being and Time. The thesis unfolds in two interrelated axes. Firstly, Heidegger will learn from each of these thinkers fundamental topics, but he will elaborate, in its fundamental ontology, its own and original concept concerning the Dasein affectivity. Secondly, the final meaning of the concept of disposedness will be related with his reading of the pathos (passion) in Aristotle. Given the plurality and the richness of the works of these three thinkers the research also highlights the current and promising aspects of affectivity for the interpretation of contemporary phenomena.