Individuals with Down syndrome (DS) present increased risk for thyroid dysfunction, especially hypothyroidism, due in increased expression of the DYRK1A gene. Objective: The aim of this study was to make a morphological functional thyroid assessment in individuals with DS. Materials and Methods: This is a descriptive cross-sectional study, consisting of 29 individuals with DS, with a mean age of 12,3 (0.66 / 36.00) years, 16 women (55.2%) and 13 men (44.8%), with a morphological/functional thyroid assessment being made comprising hormonal dose (Free T4, TSH), antithyroid antibody (TPOAb and TgAb) and ultrasonography of the thyroid. Results: Twenty-three (79.3%) individuals presented normal thyroid function while 6 (20.7%) presented with thyroid dysfunction, 4 with hypothyroidism and 2 with hyperthyroidism. Autoimmune thyroiditis and goiter were present in 27.6% of the individuals. Conclusion: Thyroid function should be assessed periodically in individuals with DS, in view of the high prevalence of thyroid dysfunction, especially autoimmune thyroiditis with consequent hypothyroidism. Key Words: Down Syndrome, thyroid, ultrasonography, thyroid dysfunction.