Sexually abused girls manifest dysregulation of physiological stress response systems. In this exploratory investigation, 14 sexually abused and 13 control girls, ages 8-15 years, recruited from a prospective, longitudinal study, underwent plasma antinuclear antibody and thyroid function tests. Thyroid function tests and plasma antinuclear antibody titers did not differ between sexually abused and control girls. However, a significantly higher incidence of plasma antinuclear antibody titers was seen in abused subjects when compared with the frequency of positive antinuclear antibody titers in a sample of 22 adult healthy female volunteers, ages 20-58 years. These findings suggest that sexually abused girls may show evidence of an alteration in normal immune homeostatic function.