Graves disease is rare in childhood and adolescence. Radioactive iodine (RAI, iodine I 131,131I) was the treatment used for these patients with undefined illness. We studied 11 patients, 10 girls and 1 boy, aged 14 to 18 years. All were treated with methimazole (ATD), with levothyroxine added when necessary to maintain euthyroidism. The ATD was administered concomitantly with the first dose of131I. In this group of adolescents, RAI was uniformly successful in treating the disease. We conclude that radioiodine should be considered as a first-line treatment option in older children with Graves–Basedow.