Metaphyseal irregularity and abnormal vertebral bodies resembling a bone dysplasia were seen in two of five children with thalassemia major who were begun on a regimen of hypertransfusion and chelation with deferoxamine before the age of 3 years. Similar changes were not seen in 22 other children in whom chelation was started after the age of 3. Whether the dysplastic bone growth was related to drug dose or age of onset of chelation could not be determined, as deferoxamine dosages differed in the two groups. Findings on radiographs included flattening of the thoracic and lumbar vertebral bodies, circumferential metaphyseal osseous defects, sharp zones of provisional calcification, and widened growth plates. Healing was noted in one of the patients after the dose of deferoxamine was decreased. Zinc levels in both affected patients did not differ from those in the 25 other chelated patients.