Sartre's and Beauvoir's antinaturalism can be seen as the rejection of the attribution of some particu-lar "nature" to specific social groups in order to deny essential aspects of their human being or even of their humanity as such. Since the existential approach starts from the lived experience and includes praxis as a crucial factor of becoming oneself, it makes possible to show some phenomena of human being and human relations that remains invisible on the abstract philosophical level. One of these central phenomena is gender, respectively gender relations, and the interconnected mecha-nisms of oppression and social exclusion. The aim of the article is to reconstruct Sartre's and Beauvoir's antinaturalist conceptions and to compare it in order to articulate their consequences for the gender problematic.