From 1992 to 1996, 19 patients had surgical resection of a substernal thyroid gland at the University of Rochester Medical Center, Rochester, New York. Based on a retrospective review of the 21 procedures performed, an algorithm for evaluation and surgical intervention is proposed. A limited medical workup is indicated and consists of a chest x-ray, thyroid function tests, computed tomography scan, and, possibly, fine-needle aspiration. Given a modestly high malignancy rate (16%) and a 37% reoperative rate, total thyroidectomy should be performed. When extensive mediastinal disease is encountered, a median sternotomy affords excellent access to the substernal thyroid gland.