Although there are no reliable incidence data for sexual abuse in the United States, estimates are that 3-5 percent of adult women and 1-2 percent of adult men were sexually abused as children. The etiology of child sexual abuse has four preconditions: the motivation to abuse children sexually, the weakening of internal inhibitors against child sexual abuse, the overcoming of external inhibitors, and the breakdown of the child's resistance. Child sexual abuse may be revealed through the victim's ambiguous or direct statements to others, marked changes in the victim's behavior, or medical conditions. Aspects of the medical assessment are the initial evaluation, interview components, physical examination, diagnostic studies, and followup care. Sexually abused children rarely exhibit effects that can be attributed only to sexual abuse, since intrafamilial sexual exploitation is typically associated with neglect, emotional abuse, deprivation, and physical abuse. In validating a child's statement of sexual abuse, it should be examined for explicit detail, and the corroboration provided by secondary factors should be explored. 20 references.