Thyroid cancer is one of the most common cancers in children, even so, it represents less than 1 % in children under 10 years of age, increasing its incidence as age increases. This entity in the pediatric age presents some differences when compared to adults. Nuclear Medicine plays an important role in the management of this type of cancer. The importance of 131I ablation of post-surgical thyroid remnants is clearly established for a better follow-up of the disease with thyroglobulin levels. In this book you will find an updated review of the medical literature concerning differentiated thyroid cancer in children.