This paper explores current thinking on the meanings of sex, gender and sexuality and on the relationship between each of these concepts. It suggests that whilst feminist theory has adopted a social constructionist view of gender and, to a lesser extent, sexuality, it has left sex to the conceptual domain of biology. It has also prioritised gender over sexuality conceptually. These issues are explored in the specific area of sexuality and law where it is argued that recent theoretical developments on sex and sexuality within poststructuralist thought have, as yet, failed to influence the dominant understanding of heterosexual relations. Arguably in the field of law and sexuality, feminism has remained wedded to a notion of binary sex and identity politics. The paper then works through two specific instances, namely rape and S/M sexual practice, to identify some of the problems associated with the latter approach. Ultimately it raises questions about whether a poststructuralist politics imbued with feminist ethics might provide us with less essentialist models of masculine/male and feminine/female sexuality without either abandoning feminist political action or falling into a new sexual conservatism.