Only 2 cases of fatal pulmonary tumor embolism have been described in patients having malignant tumors of the ovary. Both were diffuse microtumor emboli in the pulmonary arteries of elderly individuals. We present a teen-aged patient who died suddenly due to a massive tumor embolism of the right main pulmonary artery after a two-year remission of an endodermal sinus tumor of the ovary. Upon her first admission, she was treated with radical operation and insufficient chemotherapy. Two years later, she was readmitted to our hospital because of the sudden onset of dyspnea and shock; and she died 5 hours after readmission. A case of endodermal sinus tumor of the ovary with fatal pulmonary tumor embolism is described.