In many societies, women are expected to be virgins until they marry. The presence of an intact hymen confirms that a woman is a virgin. Doctors can easily test for this. Male virginity tests are unheard of.
Incidence:
In Turkey, girls can be forced by parents or school authorities to take a virginity test. If the girl is not a virgin, she can be expelled from school, charged with prostitution, and will probably face trouble from her family. Girls have committed suicide rather than take the test. No test exists for boys.