Immorality Act was the title of two acts of the Parliament of South Africa which prohibited, amongst other things, sexual relations between white people and people of other races. The first Immorality Act, of 1927, prohibited sex between whites and blacks, until amended in 1950 to prohibit sex between whites and all non-whites. The second Immorality Act, of 1957, continued this prohibition and also dealt with many other sex offences. The ban on interracial sex was lifted in 1985, but certain sections of the 1957 act dealing with prostitution remain in force as the "Sexual Offences Act, 1957".

Between 1950 and the repeal of the law in 1985, at least 19,000 people were fully prosecuted for violating the law, whereas thousands more were arrested without a trial.