The findings from a medical examination performed fairly soon after an alleged sexual assault may be very important forensically or may be virtually irrelevant in contributing to an assessment of what occurred in the incident at issue. Consensual sexual intercourse can produce genital injuries if it is the woman's first act of intercourse, if it occurs after a long period of abstinence, or if there are anatomical difficulties. Nonconsensual sexual intercourse may leave no evidence of trauma to substantiate the claim of sexual assault. The absence or presence of semen and the absence or presence of trauma constitute only a small part of the evidence in a sexual assault case. This article provides information on the circumstances that may produce various types of genital injuries to adults in both either consensual or nonconsensual sexual activity. The author states as a general rule that the genital area can be free of injury whether or not sexual intercourse is consensual or nonconsensual. Physical injuries to other parts of the alleged victim's body may, therefore, be more significant. Still, physical injuries may be minor if the victim complies under the threat of harm or death. On the other hand, resistance may result in injuries to the inside of the thighs or injuries on the limbs that result from restraint. The article lists various circumstances that tend to lead to substantial signs of injury in adults. Since adolescent or postpubertal children may be involved in sexual assault that resembles adult sexual assault, the information on adult injuries applies also to children. The perpetrators of sexual assault against prepubertal children, however, tends to function in a different way. They often use the body of the child as a masturbatory object. It is important that the actual words used by the child be considered in order to understand what they are describing. Examples of imprecise language by children in describing sexual contact are offered in this article. Children have a very good blood supply throughout their bodies, so injuries will heal within 24-48 hours of their infliction.