Oral sex refers to a variety of actions; the broadest definition includes any contact between the mouth of one individual and any part of the body of another individual, other than as a form of greeting. In the forensic context, the broad definition is useful, because analingus and breast biting are features of sexual assault. Although the prevalence of oral sex in crimes is difficult to determine, it seems to occur in at least one third of male offenses and in about one fourth of female offenses. Fellatio is the most prevalent type of oral sex, and can be revealed both from semen and saliva analyses or analyses of clothing or other items. Saliva detected by a high level of amylase on vaginal swabs indicates cunnilungus. Analingus is difficult to demonstrate due to lack of specificity of the test in current use, but substantiation of such an act is seldom needed. Oral-breast contact occurs regularly and can be shown to have taken place by examining body surface swabs and clothing. Figures, tables, and 44 references