Six and a half years after adoption, 6-to 12-year-old children reared in Romanian orphanages for more than 8 months in their first years of life (RO, n = 18) had higher cortisol levels over the daytime hours than did early adopted (EA, ≤ 4 months of age, n = 15) and Canadian born (CB, n = 27) children. The effect was marked, with 22% of the RO children exhibiting cortisol levels averaged over the day that exceeded the mean plus 2 SD of the EA and CB levels. Furthermore, the longer beyond 8 months that the RO children remained institutionalized the higher their cortisol levels. Cortisol levels for EA children did not differ in any respect from those of CB comparison children. This latter finding reduces but does not eliminate concerns that the results could be due to prenatal effects or birth family characteristics associated with orphanage placement. Neither age at cortisol sampling nor low IQ measured earlier appeared to explain the findings. Because the conditions in Romanian orphanages at the time these children were adopted were characterized by multiple risk factors, including gross privation of basic needs and exposure to infectious agents, the factor(s) that produced the increase in cortisol production cannot be determined. Nor could we determine whether these results reflected effects on the limbic-hypothalamic-pituitary-adrenal axis directly or were mediated by differences in parent-child interactions or family stress occasion by behavioral problems associated with prolonged orphanage care in this sample.