Thyroidectomy may be indicated in children with Graves' disease who have adverse reactions to antithyroid drugs or who relapse after antithyroid drug therapy. We investigated the characteristics of childhood Graves' disease from the standpoint of surgical outcome. Between 1989 and 1998, 1897 patients with Graves' disease underwent thyroidectomy and their thyroid function could be evaluated 2 to 3 years after thyroidectomy. The patients were divided into three groups according to age at thyroidectomy: 74 patients were 15 years old or less (children), 345 patients 16 to 20 years of age (adolescents), and 1478 patients 21 years of age or more (adults). The children included higher proportions of patients who had a large goiter (> 100 g), high thyrotropin-binding inhibitory immunoglobulin (TBII) level (> 50%), and small remnant thyroid (< 4 g). At 2 to 3 years after thyroidectomy, the overt recurrence rate of the children, adolescents, and adults was 9.5%, 4.9%, and 5%, respectively. The cumulative recurrence-free rate of the children, adolescents, and adults at 5 years after thyroidectomy was 82%, 90%, and 92%, respectively. Surgical complications were more frequently observed in children. Considering the aggressiveness of childhood Graves' disease, subtotal thyroidectomy with thyroid remnant less than 3 g is the procedure of choice for preventing recurrent hyperthyroidism.