Posterior mediastinal goiter extending to carotid sheath posteriorly is rare. Recently we experienced two cases of posterior mediastinal goiter presenting dyspnea due to tracheal compression. The one was a 48-year-old female with mediastinal tumor shadow on chest roentgenogram . The other was a 54-year-old female with palpable mass on neck and huge mediastinal mass. These masses were resected completely through the right posterolateral thoracotomy and median sternotomy respectively. The postoperative courses were uneventful.