A 20-year-old man was admitted to our hospital with persistent cough and dyspnea. He had bilateral distention of the jugular veins, and swollen lymph nodes were palpable in the right subclavicular region. Plain X-ray and computed tomography (CT) of the chest showed a solid soft tissue mass in the upper mediastinum, with leftward displacement of the trachea and complete obstruction of the superior vena cava. Mediastinal radiotherapy (1.8 Gy/day) and methylprednisolone (100 mg/day) were started immediately. Biopsy of the right subclavicular lymph nodes revealed metastatic seminoma. The patient was referred for chemotherapy, which was performed with a combination of cisplatin, bleomycin and etoposide (BEP). A partial response was observed after completion of 3 cycles of chemotherapy, but there was no further tumor shrinkage after additional salvage chemotherapy. The patient is being followed up on an outpatient basis and has been free of recurrence for 32 months after intensive treatment.