Objective: To assess iron deficiency (ID) in international adoptees after adoption. Study design: Participants (n = 37) were adopted into the United States from Eastern Europe before they were 24 months of age. Baseline (within 1 month post-adoption) and follow-up (6 months post-adoption) assessments included routine post-adoption clinical evaluations, anthropometrics, dietary intakes, and iron measures (hemogram and serum analysis). Results: At adoption and follow-up, mean percent transferrin saturation and mean corpucuscular volume were low compared with the US population. Mean serum ferritin concentration became lower than the US population at follow-up, although the mean daily iron intake was more than the Recommended Dietary Allowance. Participants with Giardia lamblia at baseline had more compromised iron status at baseline and follow-up. Growth rate (change in z-score/months between assessments) was negatively correlated with change in serum ferritin concentrations between baseline and follow-up (r = -0.34; P < .05). Conclusions: International adoptees had compromised iron status, with ID more prevalent in participants with G lamblia, a parasite that may interfere with iron absorption. The persistent ID at follow-up was likely caused by the erythropoietic demands of catch-up growth.