My paper follows the discussion opened by Jon Stewart’s recent book on Hegel’s concept of alienation and its influence on nineteenth-century thought, specifically in the chapter devoted to the concept of alienation in S. Kierkegaard. To begin the article, before I get to the central problem I will try to classify the two basic types of alienation we can encounter in the whole of Kierkegaard’s work: the religious (or universal) alienation of the Christian from the world and the existential alienation of man from himself: despair. The core of the study is devoted to an analysis of Kierkegaard’s concept of despair, which Kierkegaard understands as one of the basic structural moments of human subjectivity. Here I will focus particularly on portraying and analyzing the spiritual and dialectical nature of despair. My main intention, however, will be to interpret despair as a fundamental form of the self-alienated self. For despair expresses a state of existence in which the self is not oneself, a state in which the self seems to be separated from its own true self. This interpretation of mine corresponds to Stewart’s view in its basic features. At the end of the paper I will attempt to outline my own understanding of despair as self-alienation within the broader dialectics of existence in Kierkegaard, using the Hegelian model of dialectics.