Through interviews with 50 female sex-workers in the Hillbrow/Berea/Joubert Park area of Johannesburg, this paper explores sexual negotiations between men and women in the sex industry. This paper focuses on factors that affect sexual decision-making including safer sex practices. In moving beyond approaches that emphasize women's 'powerlessness' in sexual negotiation, this article focuses on ways in which sex-workers capitalize on clients' reluctance to use condoms in sexual exchanges. We emphasize sex-worker's agency and use a broader, Foucauldian understanding of power, which couples power with resistance. Further, this paper examines other elements of the sex industry that contribute to unsafe sex such as competition between women for clients and violence in the industry. Finally, this paper suggests that HIV-prevention programs take cognizance that power negotiations between men and women cannot be simplistically understood as men having power and women being powerless. Rather, this article contributes to a growing body of literature in medical anthropology, which elucidates the complexities of sexual negotiations between men and women. This focus on agency is important in trying to lessen the stigma and discrimination that sex-workers face at the hands of clients, pimps/managers, police and health care workers.