A 23-year-old man with a right scrotal mass and back pain was referred for further treatment after right radical orchiectomy for testicular cancer. CT scans brought by the patient showed extensive metastasis to the retroperitoneal lymph nodes with no lung involvement. α-Fetoprotein and human chorionic gonadotropin were elevated preoperatively (384 ng/ml and 112 mIU/ml, respectively). Confirmation of the histopathologic examination revealed a mixed germ cell tumor (95% immature teratoma and 5% embryonal carcinoma). We started the patient on chemotherapy with bleomycin, etoposide, and cisplatin (BEP). After a single course, tumor markers began to normalize, but there was radiologic evidence of continued growth of the retroperitoneal mass and new metastases in the lung. The patient was given 2 courses of salvage chemotherapy with etoposide, ifosfamide, and cisplatin (VIP). However, the mass and lung metastases continued to progress, and the patient was growing rapidly intolerant of the side effects of treatment (i.e., nausea, appetite loss, and pancytopenia). After thorough discussion with the patient and his family, we decided to start the patient on interferon (IFN)-α therapy. Natural, nonrecombinant IFN-α (OIF, Otsuka, Japan) 5,000,000 IU was administered twice weekly with approval of the ethics committee of our institution. The patient responded moderately with marked deceleration of tumor growth and stabilization of the lung metastases. He is alive and well at 16 months on IFN-α therapy.