In the 1960s, sports authorities grew increasingly concerned with two issues — doping and sex — and experimented with different ways to test for both. The growing significance of sport in the Cold War era made it clear that affidavits from team and family physicians could no longer suffice — the documents were too easily falsified in the quest for athletic supremacy. Although World War II halted most major international sports competitions, the conflict did little to quell apprehensions about the sex of women athletes. Athletic officials next turned to the buccal smear, which was a relatively new cytological test. Technicians looked for the presence of the second inactive X chromosome or Barr body. The logic is even more confounding when juxtaposed with testosterone-related regulations for trans athletes. The discussion of endogenous and exogenous testosterone highlights the complexities of defining sex for the purpose of elite sport competition.