Retrosternal goiters are commonly situated in the anterior mediastinum, but according to the literature, 10–15% are located in the posterior mediastinum. The authors report two cases of enormous goiter in the posterior mediastinum. Case 1 was a 60-year-old man. His mass measured 12 × 9 × 8 cm and was combined with trachea compression and superior vena cava syndrome. Case 2 was a 59-year-old woman. Her mass measured 9 × 6 × 6 cm and she was admitted with the complaint of dysphagia. Both patients were discharged from hospital after successful operations. They reported normal activities in the follow-up.