In prepubertal children, teratoma is a benign tumor, whereas in adolescents and adults, it behaves as a malignant neoplasm. Adult patients without evidence of metastases may be candidates for surveillance after orchiectomy, and those with low-volume or borderline retroperitoneal metastases thought to contain teratoma might best be managed by surgery, as teratomatous deposits do not respond to chemotherapy. Patients with larger retroperitoneal metastases may be given chemotherapy before surgery to reduce or eliminate other germ-cell elements. Teratomatous masses persisting after chemotherapy are excised by most clinicians, in part to obtain a pathologic diagnosis. In childhood tumors, inguinal orchiectomy or enucleation is sufficient if one is certain the lesion contains only teratoma.