Sexual abuse occurs when a child is involved in sexual activities that the child cannot comprehend, for which the child is developmentally unprepared and cannot give consent, and/or that violate the laws or social taboos of society. Sexual abuse encompasses activities that range from rape to physically less intrusive sexual contact. The diagnosis of sexual abuse and the protection of the child from further harm depends in part on the pediatrician's willingness to consider abuse as a possibility. Because children who are sexually abused generally are coerced into secrecy, a high level of suspicion may be required to recognize the problem. Among the more specific signs and symptoms of sexual abuse are rectal or genital bleeding, sexually transmitted diseases, and developmentally unusual sexual behavior. Pediatricians who observe these signs in child patients should at least consider the possibility of abuse and should make a report to child welfare personnel if no other diagnosis apparently explains the findings. Pediatricians who suspect sexual abuse should inform the parents of their concerns in a calm, non-accusatory manner. A complete history, including behavioral symptoms and associated signs of sexual abuse should be obtained. The primary responsibility of the pediatrician is the protection of the child, which sometimes requires a delay in informing the parents while a report is made and an expedited investigation by law enforcement and/or child protective services can be conducted. This paper details the procedures for taking a history and interviewing the child, conducting an appropriate physical examination, and obtaining relevant laboratory data. The physical examination alone is infrequently diagnostic in the absence of a history and/or specific laboratory findings. This paper reviews diagnostic considerations and emphasizes the importance of maintaining detailed and accurate records, which may be required for court proceedings. The paper concludes with discussions of treatment and legal issues. 2 tables and 29 references