During 1987-1989, 14 (14.6%) of the 96 children who tested positive for the human immunodeficiency virus (HIV) and were followed up by the Duke University (Durham, NC) pediatric acquired immunodeficiency syndrome team were confirmed to have been sexually abused. Every sexually abused child was evaluated for each of five modes of HIV transmission, and in nine children the pathway was identified. Four of the study children acquired HIV from child sexual abuse and in six, abuse was a possible source. Transmission by child sexual abuse was the most frequent of the proven modes of acquisition of HIV in this population. The other proven modes of acquisition were vertical transmission (n = 3) and HIV-contaminated blood transfusion (n = 2). Twelve males were identified (n = 8) or suspected (n = 4) of being perpetrators. Three knew themselves to have HIV at the time of an assault and eight were aware that the child had HIV at the time of an assault. There was no indication from any child that "safe sex" precautions had been observed. Children with HIV infection had multiple risk factors for abuse or neglect. The sociological descriptors of the lives of the 14 abused children showed multiple known risk factors for sexual abuse that also overlapped with known risk factors for or sequelae of the acquisition of HIV infection. These included drug abuse and alcoholism in the home, prostitution of a parent, lack of parenting, poverty, and chronic illness of the child. Prevention efforts should recognize that children as well as adults are at risk for sexually transmitted HIV infection.