The patient was a 64-year-old female with an abnormal shadow on chest X-ray examination. Chest computed tomography (CT) revealed mediastinal goiter. Concerning the laboratory data, the FT3 and FT4 values were within the normal ranges. However, the thyroid stimulating hormone (TSH) level was slightly decreased. The tumor involved the paratracheal region along its posterior surface, extending an area below the bifurcation of the trachea. Therefore, median sternotomy was chosen to remove the tumor. Pathologically, no nuclear atypia was noted in the follicular epithelium, suggesting adenomatous goiter. The patient was discharged without complications. There has been no relapse during the 9-month postoperative follow-up.