Objective: To report a rare case of nonseminomatous extragonadal germ cell tumor in a 66-year-old female with primary yolk sac tumor of the mediastinum. Clinical Presentation and Intervention: A 66-year-old female was admitted to our hospital with a history of chest pain for 1 month. Computerized tomography of the thorax showed a left paracardiac mass adjacent to the aortic arch, left main pulmonary artery and pericardium. Total surgical excision could not be performed, but several biopsies which were taken through a thoracotomy revealed yolk sac tumor of the mediastinum. Systemic chemotherapy was started, but no response was observed and the patient died after one course of chemotherapy. Conclusion: Nonteratornatous mediastinal germ cell tumors are virtually nonexistent in women. To our knowledge, this is the oldest female patient with a primary mediastinal germ cell tumor. Chemotherapy was not effective especially in an old patient. We suggest surgery should be considered as primary treatment modality if diagnosis is made at an early stage. Copyright (C) 2002 S. Karger AG, Basel.