Abstract
Benign mediastinal teratoma accounts for 60% of all mediastinal germ cell tumors, which in turn account for 15-20% of all anterior mediastinal masses. It is frequently associated with compressive effects of surrounding structures. Total surgical excision is curative and life saving also. We are presenting a case of giant benign cystic mediastinal teratoma which underwent surgical excision but long term compressive effect on lungs resulted them to be small in size compared to thoracic cavity even six months postoperatively.