We report a case of life-threatening germ cell tumor in abdominal cryptorchidism. A 32-year-old man presented with a three-month history of dyspnea, loss of appetite, general weakness and a large abdominal mass. Physical examination revealed vacancy of the right scrotal contents. Chest radiograph showed massive left pleural effusion. Abdominal ultrasound revealed ascites, right hydronephrosis and the presence of an 18 x 15-cm heterogeneous echogenic mass in the upper abdomen and right iliac fossa. Abdominal computerized tomography (CT) revealed the presence of a large heterogeneous tumor and an enlarged (4 x 4-cm) retroperitoneal lymph node. Sonoguided needle biopsy of the abdominal mass demonstrated malignant cells of an uncertain type and origin. Serum alpha-fetoprotein (AFP) and beta-human chorionic gonadotropin (beta-HCG) concentrations were elevated. Under the diagnosis of metastatic nonseminomatous germ cell tumor in abdominal cryptorchidism, the patient received three cycles of cisplatin-based combination chemotherapy followed by resection of the abdominal residual cryptorchid tumor. Histologically, the tumor showed marked necrosis without viable cancer. The patient had remained free of disease for seven months following surgery.