The purpose of this article is to analyse the relationship – conceptualised by Michel Foucault – between politics (in the sense of a political game, governing or applying techniques of power) and truth. Here truth is understood in ontological terms (related to the moment of disclosure, revelation) rather than in linguistic and epistemological terms (related to the act of judgement). By outlining some mutual relations between politics and truth, the author tries to show how politics/power determines truth and how truth affects politics. He is particularly interested in parrhesia, which is a form of truth that has emancipatory or even revolutionary potential, i.e. it introduces a difference into the relations of power functioning at a given moment.