Pediatric patients with Graves' disease (n=26) were studied longitudinally by magnetic resonance imaging of the orbits, allowing an assessment of the enlargement of the extraocular muscles and orbital volume variations. The positive outcome of Graves' ophthalmopathy correlated with low TRAb (autoantibodies to thyroid-stimulating hormone receptor) titers at diagnosis and during follow-up and with prepubertal condition at diagnosis.