This paper examines Simone de Beauvoir’s reading of the 18th century writer and libertine Marquis de Sade, in her essay “Must we Burn Sade?”; a difficult and bewildering text, both in pure linguistic terms and philosophically. In particular, Beauvoir’s insistence on Sade as a “great moralist” seems hard to reconcile with her emphasis, in The Ethics of Ambiguity, on the interdependency of human beings and her exhortation to us to promote other people’s freedom, as well as the aspiration of The Second Sex to equal relations between the genders. While earlier scholars addressed the ethico-political implications of Beauvoir’s essay, they insisted that the ambiguity so fundamental in her philosophy is denied by the Sadean hero, and that the Other can never be attained in his system. In this essay, I argue that Sade paradoxically emerges as an ethical model in Beauvoir’s text: as a writer, he assumes the ambiguity of the human condition in the extreme. Further, Sade reveals the potential of sexuality if it is explored in a form of eroticism that largely transgresses behavior constructed as normal: his writings open up new forms of existence, where, contrary to prevailing ideas, woman’s sexual freedom is claimed as equal to man’s, where genders are unstable and heterosexuality no longer the standard. Beauvoir’s fascination with Sade in this essay can be linked with the seemingly unresolvable asymmetry in the relation between men and women in The Second Sex: in his writings is revealed sexuality’s potential to subvert patriarchal norms and mystifications, and perhaps, in the end, even gender itself.