Mediastinal teratomas are rare and represent less than 10 per cent of all mediastinal tumors. Almost all arise in the anterosuperior mediastinal compartment, and most symptoms, when present, result from compression of adjacent structures. They contain different tissues derived from all three germinal layers, with the prevalence of ectodermal elements which can include hair, teeth and sebaceous material. Benign teratomas may rupture into adjacent organs. Up to 36% of all mediastinal teratomas rupture, most frequently into the lung and bronchial tree, followed by the pleural space, pericardial space, or great vessels. The signs and symptoms of a ruptured teratoma vary with the structures involved. We report a case of mediastinal teratoma ruptured spontaneously in a 18 year old female who experienced 4 or 5 times of hemoptysis for 1 year and sudden onset of pleural effusion, pericardial effusion and pneumonia.