Most research on transactional sex frame men as buyers and females as sellers of sex. We conducted a systematic mapping review of the empirical research on transactional sex where women form the demand (buyer) and men the supply (seller). We included 46 studies, of which 25 explicitly researched women as buyers of sex from male sellers, and 21 studies where this topic was a subset of larger topics. The majority of research on women who trade sexual services from men is published in the last 15 years, by female researchers, using cross-sectional or qualitative/ethnographic design, and from the perspective of males as sellers. While the women appear to be mature and financially independent, the men are young and socioeconomically vulnerable. Men's main motivation for the sexual-economic exchanges with women is financial, whereas women's motivations are largely satisfaction of sexual needs and a stereotyped erotic fantasy of black male hypersexuality. Condoms are often not used. Our review shows that there is a - possibly growing and diversifying - female consumer demand for male sexual services, and transactional sex where women trade sex from men is a complex social phenomenon firmly grounded in social, economic, political, and sexual relations.