The present paper analyzes the causes, signs and symptoms of hyperthyroidism in children and the problems, complications and results associated with the various therapeutic regimes. Childhood hyperthyroidism is usually due to Grave's disease, an autoimmune thyroid disease. Genetic factors are also involved in its development. The diagnosis and in particular the differential diagnosis with Hashimoto's thyroiditis are discussed. Treatment of Graves' disease is controversial, but medical therapy is commonly accepted as the treatment of choice. Some dosage schedules of antithyroid drugs are considered, and some techniques for predicting remission status and relapse of disease are reported. Both the minor and more serious complications of medical therapy are examined. Careful follow-up for the development of hypothyroidism is advocated, especially in patients treated with radiation or surgery. Autonomous hyperfunctioning thyroid adenoma is rare, but occurs even in childhood, and can degenerate into carcinoma.