In May 1954, the story broke internationally of Marta Olmos, recipient of the first widely known, male-to-female sex reassignment conducted in Mexico. Her doctor, Rafael Sandoval Camacho, claimed that homosexuality could be cured and that, through transitions, queer Mexicans could be made into ‘socially useful’ citizens. While initially celebrated as a scientific triumph placing Mexico among elite nations, and receiving support from individuals close to the Ruiz Cortines administration, opinions soured as critics – physicians, politicians, cartoonists and clerics – condemned Marta for renouncing manhood through a fraudulent cure that threatened the binary sex/gender order underpinning Mexican nationalism. Sex reassignment, understood through foreigners including Christine Jorgensen and associated with ‘anti-social’ queer Mexicans, thus exemplified misplaced priorities during a period in which the state sought to ‘modernise patriarchy’. While self-affirming for Marta and permitted unofficially through state indifference, sex reassignment became seen as anti-Mexican. Thus, Marta's case illuminated how the state reconciled development with policing its patriarchal order.