Sex testing by the International Amateur Athletic Federation (IAAF) in 1966 and 1967
There are some reports that female athletes at IOC (International Olympic Committee) events in the 1960s were required to do a "nude parade" in front of medical experts to try to verify if their biology was feminine enough.
"[A]n earlier Olympic era, when every female athlete was required to submit to a sex-verification test. ... At first, women were asked to parade nude before a panel of doctors to verify their sex. At the 1968 Olympics in Mexico City, officials switched to a chromosomal test."
"[I]n 1966 international sports officials decided they couldn’t trust individual nations to certify femininity, and instead implemented a mandatory genital check of every woman competing at international games. In some cases, this involved what came to be called the 'nude parade,' as each woman appeared, underpants down, before a panel of doctors; in others, it involved women’s lying on their backs and pulling their knees to their chest for closer inspection."
"In 1966, the International Amateur Athletics Federation (IAAF) required athletes to undergo a physical inspection by three female gynecologists at the European Championships in Track and Field [Budapest, Hungary]... In the same year, a pelvic examination was required for athletes entered in the Commonwealth Games in [Kingston] Jamaica. At the European Cup Track and Field events in 1967, the IAAF added chromosome testing to the visual inspection (2003, p. 87)."
"Simpson, et al. (2000) also report that 'physical inspection was made of disrobed female athletes' at the 1966 European Track and Field Championships and the 1967 Pan American Games in Winnipeg [Canada] (see also Puffer, 1996); and that 'gynecologic examinations were performed' at the 1966 Commonwealth Games (p. 1568)."
"...the only hard evidence for the naked parades came from IAAF-sponsored events like the World Championships and the Commonwealth Games. [I]n the IOC archives [I] only found reference to lab-based testing. That said, the IOC was certainly 'in' on the IAAF plans and was watching them carefully. There was overlap in their medical advisors (there still is) and femininity testing was regularly on the agenda of IOC meetings of that time (personal communication, 17 May, 2013)."
"Bruce Kidd reports that several scholarly papers on sex testing were presented at the annual meeting of the North American Society for Sport History (Halifax, NS, CANADA, 24-27 May, 2013): '[t]he consensus is that the visual parades were limited to IAAF events in 1966 and 1967 before the chromosome test was introduced in late 1967' (personal communication, 26 May, 2013)."
Puffer, J. (1996). Gender verification: A concept whose time has come and passed? British Journal of Sports Medicine, 30(4): 278.
Ritchie, I. (2003). Sex tested, gender verified: Controlling female sexuality in the age of containment. Sport History Review, 34: 80-98.
Simpson, J., A. Ljungqvist, M. Ferguson-Smith, A. de la Chapelle, L. Elsas II, A. Ehrhardt, E. Ferris & A. Carlson (2000). Gender verification at the Olympics. Journal of the American Medical Association. 284(12): 1568-9.