Sex discrimination in the workplace happens when discriminatory actions are taken against an employee because of their sex. According to United States law, sex discrimination is unlawful not only in the workplace, but in other areas as well. Sex discrimination workplace laws are headed by federal legislation, and may also be specified under a city or company's employment law to extend protection.

Sex discrimination can include a variety of actions; however, it is only illegal when the actions are based solely on a person's gender. Employees are not necessarily required to be treated fairly, but the unfair treatment cannot occur as a result of the person's sex. A woman who is denied a promotion, for example, has not been victimized by sex discrimination just because a male has been offered a promotion. For this to be sex discrimination, there would need to be proof that the employee was of equal status to the male and was only denied based on her sex.