Substernal goiter may be defined as any thyroid enlargement that has 50 to 100 % of its mass inferior to the thoracic inlet. Ectopic substernal goiters are rare, and most substernal gaiters arise from cervical thyroid gland. Fifteen to fifty percent of these patients are asymptomatic. Symptoms, when present, are usually the result of tracheal or esophageal compression. Symptoms are often positional. Standard chest roentgenograms are often diagnostic, but computed tomographic or radioactive iodine scans may be helpful. In symptomatic patients or those in whom explorations are undertaken for diagnostic purpose or exclude carcinoma, surgical removal is indicated. Although cervical thyroids with substernal extension may be safely and successfully removed through a cervical incision, primary substernal goiters by definition derive their blood supply from within the thorax and are better approached by splitting the sternum or through a posterolateral thoracotomy. Recently we experienced a child fist sized secondary posterior mediastinal goiter in 55-year old female. The mass was completely removed through right posterolateral thoracotomy without any complications. The postoperative courses were uneventful.