With the circulation of pharmaceutical sex hormones, a key aspect of sex—that defined by hormonal action—is now exogenous to the body. For this reason, the use of sex hormones is carefully regulated. The chapter considers a range of practices that bring into question sexual dualism and the social construction of the sexed body. Through an analysis of the diverse prescribed and informal hormonal regimes adopted in Salvador, this chapter shows how the uses made of sex hormones re-inscribe sexual dualism at the point at which it would seem to be menaced. It shows how the uses made of sex hormones trouble not only sex and gender, but the distinction between them. This troubling of sex/gender takes place in a context where the feminization of male bodies is not legitimated while the masculinization of female bodies seems increasingly desirable. Given the many biological and social elements that are required to make “sex,” and not just “gender”, efforts need to be deployed to re-assemble them with the consistency that makes us blind to the manufactured aspect of “sexual identity”. The chapter explores how sex hormones, in their local guise as hormônio, are called upon in this task.