Since the transformation of Christine Jorgensen, a male-born American who received gender confirmation surgery in 1952 to become a woman, people across the world have debated the technological, legal, and moral parameters of this procedure. Even as developments in plastic surgery, endocrinology, and related fields enabled such bodily changes, a transnational account of scientific modernity must also attend to the conditions in which this procedure took root in specific places, traveled to others, and became part of embodied livelihood. Using authoritarian South Korea as a site of investigation and criticism, this paper asks a series of questions that aims to localize and humanize the global politics of “sex reassignment.” These questions pivot around changing definitions of body atypicality, uneven access to surgical modifications, and the overall affordability of such procedures, as well as the lived experiences of gender- and sexually-variant Koreans in school, family, the workplace, and other normalizing institutions. Using medical and popular texts from the 1950s to the 1980s, I first trace how doctors sought to violently modify the genitalia of intersex persons to maintain a dimorphic model of corporeal difference. I then compare their lives to gender-nonconforming and transgender-identified people who desperately sought to modify their bodies through a variety of surgical and non-surgical techniques, some of them quite dangerous. Throughout, I situate their ongoing struggles for survival in intersectional debates that aim to empower the lives of gender and sexual minorities in South Korea and other places of scientific modernity across the world today.