A retrospective case-control study was undertaken among patients followed at the Texas Children's Hospital Retrovirology Clinic to determine the risk factors for Staphylococcus aureus infection. A total of 28 episodes of S. aureus infection were identified from 20 patients. Case patients had more advanced HIV disease as measured by CD4 T-cell counts, log10 human immunodeficiency viral load, and Centers for Disease Control and Prevention category of disease, than controls.