Most intrathoracic goiters are located in the anterior mediastinum, frontal to the recurrent laryngeal nerve and anterolateral to the trachea. Posterior mediastinal goiters account for only 10 to 15% of all intrathoracic goiters and arise from the posterolateral portion of the thyroid gland. We present a case involving a 59-year-old man with history of gradual-onset dyspnea who was referred to us for evaluation of a large mediastinal mass. He had undergone bilateral thyroid lobectomy for a cervical goiter 10 years previously, with no subsequent complications. Contrast-enhanced computed tomography demonstrated a large, well-circumscribed mass extending paratracheally from the thoracic inlet to the posterior mediastinum. The mass was removed via a transcervical and transthoracic approach.