© 2022 French Society of PediatricsObjective: Hashimoto's thyroiditis and Graves’ disease are autoimmune diseases of the thyroid gland, and both diseases are diagnosed with ultrasound findings and autoantibody height. However, ultrasound (US) findings may be normal in both diseases rarely. In some pediatric studies, it was reported that shear wave velocity values in autoimmune thyroiditis were significantly higher than normal thyroid parenchyma and it was recommended to be used as a diagnostic method. Our study will address the evaluation of patients with Hashimoto's thyroiditis and Graves’ disease by thyroid elastography and the role of this method in diagnosis. Materials and methods: 28 patients with Hashimoto's thyroiditis, 20 patients with Graves’ disease and 40 healthy controls were enrolled in our study prospectively. Thyroid Elastography and US were applied to all patients. Results: In US, Hashimoto's thyroiditis had a hypoechoic echo pattern compared to graves’ disease (p < 0.05). When shear wave velocity (SWV) value of children with Hashimoto's thyroiditis and Graves’ disease were compared with the control group, thyroid tissue showed more stiffness in both disease groups (p = 0.001). When SWV values were compared between Hashimoto's thyroiditis and Graves’ disease, there was no statistically significant difference (p = 0.73). Conclucion: SWV values were found to be higher in children with Hashimoto's thyroiditis and Graves’ disease compared to the control group and contributes to the diagnosis of these diseases. However, the elastography technique alone is not sufficient to differentiate. Hashimoto's thyroiditis and Graves’ disease.