Here we review the etiology, diagnosis, differential diagnosis, and clinical presentation of hyperthyroidism in neonates/infants, children, and adolescents and the standard and adjunct modalities used for its treatment. The most common cause of hyperthyroidism in pediatric patients is Graves' disease. The main options for its management include antithyroid drugs, surgery, and radioiodine therapy. Despite collective experience covering more than 4 decades in the management of hyperthyroidism in children, controversy still abounds regarding the choice of treatments. None of the current treatment options is ideal. Each has risks and selection should be tailored to individual patients, especially in view of the absence of large, prospective, randomized outcome studies. Finally, we discuss the diagnosis and management of less common causes of pediatric hyperthyroidism, including non-autoimmune causes in neonates, autonomously functioning thyroid adenomas, destructive thyroiditis, excessive or inappropriate thyroid-stimulating hormone production, excessive ingestion of thyroid hormone and exposure to large, stable iodine loads.