Sexual assault is a frequently occurring violent crime. Sexually transmitted diseases (STDs) may be acquired during assault. Reported rates of gonorrhea and syphilis in adult victims range from 6% to 12% and from 0% to 3%, respectively. The risk of acquiring other STDs cannot be quantified, although the risk of infection with Chlamydia trachomatis appears highest. In abused children, gonococcal and chlamydial infections are the most frequent findings. In both adults and children, postassault infections with viral agents of STDs, including herpes simplex viruses, hepatitis B virus, and human immunodeficiency virus, have been described. Sensitive, competent care for victims of sexual abuse includes evaluation for STDs soon after the assault and during follow-up.