This paper reviews and critiques research on online illegal drug markets, arguing that existing conceptualisations and methodological approaches have resulted in a very limited discussion of women and questions of gender. The first part lays out the stereotypes and unarticulated assumptions that enable questions about women and gender to be side-lined, as follows: i) that online anonymity rules out knowing about gender in online drug markets; (ii) that online drug markets are male-dominated spaces; and iii) that women are limited to minor or peripheral roles in those markets. Our aim is to make apparent, and challenge the marginalisation of enquiry about women and gender in existing scholarship about online illegal drug markets. In the second part, we draw on scholarship on women and gender in the drug trade more generally to consider what studying online illegal drug markets might add to our understanding of both women’s participation in these markets and the way in which gender is more widely performed. We consider whether online markets may facilitate women’s participation (due to anonymity, for example), or whether online drug markets replicate gendered stratifications characteristic of offline markets. We also explore the potential significance of women’s participation in online illegal drug markets for harm reduction services. In conclusion, we suggest that future research should challenge the assumption that we can understand online markets without thinking about gender and outline the steps towards building a gendered perspective in this area.