Patients who have not had prior biopsy or surgical resection undergo biopsy (if feasible) or surgical resection. Patients with mature or immature teratoma undergo observation. These patients who relapse (i.e., tumor regrowth) may undergo further surgical resection unless tumor markers are significantly elevated. If the tumor markers are significantly elevated, these patients proceed to JEB chemotherapy according to risk group. Patients with all other malignant germ cell tumors are assigned to 1 of 3 treatment groups according to risk.