Ectopic intrathyroidal thymic tissue, with coinciding intrathymic parathyroid tissue, is a very rare occurrence that is most often found incidentally in adults during surgery. We report a 23-year-old female who presented with Graves disease refractory to medical treatment. Radioactive iodine uptake demonstrated increased, diffuse uptake in the region of the thyroid. The patient underwent a total thyroidectomy and right inferior parathyroidectomy which was found enlarged intraoperatively. Histopathologically, surgical specimen demonstrated characteristics of intrathyroidal thymic tissue and intrathymic parathyroid tissue. Intrathyroidal thymic tissue can be identified preoperatively on ultrasonography, but the significance of this finding is unknown.