Differentiated thyroid carcinomas are TSH-dependent tumors induced by genetic and environmental factors. They may be found on 3-12% of single thyroid lesions. Females are more affected than males (F:M 3:1). The combined action of genetic and environmental factors induces the development of these tumors. The cornerstone of diagnostic evaluation is Fine Needle Aspiration (FNA). Size tumors > 2.5 cm and age > 45 aa are unfavorable prognostic factors. Radical surgery is the first choice therapy followed by hormone suppressive therapy and/or I131. Follow-up is based on WBS and serum Tg evaluation. Moreover recombinant TSH offers a new approach in the field of relapse diagnosis and therapy.