the idea of human dignity has been an object of a great number of philosophical debates and occupies a relevant place in international law. nevertheless it is a controversial concept. whereas some thinkers hold that it is a question of a fundamental ethical criterion that also offers the basis for legal obligation not only in the area of politics but also, for example, in biomedicine, others are skeptical with respect to the contributions and to the ethical and legal scope which a criterion of human dignity could have. in this article i propose to clarify critically the positions of kant and habermas regarding the notion of "human dignity". i divide my explanation in three parts: in the first part, i briefly point out what "human dignity" consists in kant's ethical-philosophical thinking (1). then, i examine habermas' comprehension of human dignity and the arguments he presents in relation to the treatment that human life and persons should receive (2). finally, i present a critical evaluation of the contributions of kant and habermas concerning the concept of human dignity in order to show their scope and limitations (3).