A 31 year-old man with a biopsy-proved retroperiotoneal yolk sac tumor was referred to our clinic. Physical examination revealed a thum- tip sized left supra-clavicular mass, a huge right abdominal mass and a tiny hard mass of the right testis. On CT scan, the abdominal tumor, 13 cm in diameter, encircled the inferior vena cava. Serum levels of LDH, AFP and hCG-beta were 2,585 U/l, 19,922 ng/ml and 6.6 ng/ml, respectively. No visceral metastasis was found. Following the right high orchiectomy, 4 cycles of VIP chemotherapy consisting of ifosfamide, etoposide and cisplatin were given, which resulted in partial response of the retroperitoneal mass and complete regression of the supraculavicular node with normalization of all tumor markers. Thus, retroperitoneal lymph node dissection was carried out. Because of the marked adhesion to the tumor, the inferior vena cava was segmentally resected together with the tumor, which was followed by reconstruction of the vena cava using a 16 cm long polytetrafluoroethylene graft, since no collateral venous route was found on the pretreatment venacavography. Histologically, the tumor was nearly necrotic with mature teratoma in small part. Postoperative clinical course was uneventful except feeling of numbness at the right tip toe, and the inferior vena cava has been patent 18 months after the operation with no evidence of recurrence.