Malignant ovarian germ cell tumors (OGCT) and sex cord-stromal tumors (OSCST), each of which account for less than 5% of all ovarian malignancies, are much less common than epithelial ovarian cancer. In young patients suspected of having an OGCT, laparotomy is initially indicated for both diagnosis and treatment. For most patients, unilateral salpingo-oophorectomy with preservation of the contralateral ovary and the uterus is appropriate. The basis for this surgical approach is retrospective studies that show an equivalent cure rate for patients who undergo unilateral or bilateral adnexectomy. No prospective studies have compared unilateral with bilateral adnexectomy. Surgical staging is also important to determine the extent of disease, to determine prognosis, and to guide postoperative management. If metastatic disease is encountered during initial surgery for OGCT, the same principles of cytoreductive surgery that have been applied to surgically manage advanced epithelial ovarian cancer are recommended, with resection of as much tumor as is technically feasible and safe. For all OGCT patients except those with well-documented stage IA grade 1 pure immature teratoma or stage IA pure dysgerminoma, postoperative chemotherapy is indicated. The current recommended regimen for OGCT is bleomycin, etoposide, and cisplatin--a combination that appears to result in at least a 95% cure rate for stage I disease and at least a 75% cure rate for advanced-stage disease. For patients with metastatic dysgerminoma, chemotherapy, which has the advantage of preserving fertility in the majority of patients, has supplanted radiotherapy as standard treatment. For patients with OSCST, no standard therapy exists. Surgery alone is currently acceptable treatment for all patients with OSCST except those who have metastatic disease or Sertoli-Leydig cell tumors with poor differentiation or heterologous elements. Currently, platinum-based combination chemotherapy is favored for these latter patients, but the activity of such regimens appears only modest.