A-7 year-old girl who was admitted to Dr. Sami Ulus Children's Hospital was diagnosed as cord compression at Thoracic 6-7 level. Pathological examination of the removed material revealed thyroid tissue, Aspiration material from the thyroid nodule was also benign. The mass causing cord compression was diagnosed as mediastinal ectopic thyroid tissue. Review of the literature showed that this is the first recorded case of mediastinal ectopic thyroid tissue causing cord compression.