The International Ski Federation (FIS) instituted sex testing protocols in 1967. In doing so, it followed the example set by the International Amateur Athletic Federation (IAAF) and became the second international federation to institute some form of compulsory sex control, before the International Olympic Committee implemented its sex verification policy in 1968. Despite initially looking to the track and field federation for guidance, the FIS eventually diverged in procedure, method, and timing. It required testing occur in women skiers’ home countries before competition, introduced testosterone levels into the equation, and continued mandatory checks until 2000, after the IAAF had abandoned routine, on-site controls. An analysis of the FIS sex verification policies exposes a deep and long-lasting anxiety about the appropriateness of women in all sports, not just in track and field; identifies the introduction of hormonal analysis into sex verification; and shows the unintended consequences of sex testing when done at the national level.