The case report of a 64-year-old Jewish woman para 3 with menopause since age 50 is presented. Hirsutism of face but loss of scalp hair and hoarseness of voice had been noted for over 5 years. 5 months previously a basosquamous carcinoma was removed from her face. The patient was moderately obese and masculine in appearance. Blood pressure was 210/120 mm Hg. Glucose tolerance was diabetogenic. Vaginal cytology showed mostly basal and parabasal cells. Peripheral plasma testosteone was increased to 325 ng/100 ml (normal 15-70). Selective catheterization of right ovarian vein compared with that of inferior vena cava left adrenal vein and left ovarian vein showed a marked increase in testosterone to 635 ng/100 ml. A diagnosis of virilizing tumor of the right ovary was made. At laparotomy the right ovary was normal in size with a small protrusion on the surface. Total hysterectomy and bilateral salpingo-oophorectomy were done. 7 days postoperation plasma testosterone fell to 13 ng/100 ml and urinary gonadotropins rose to 1320 mouse units. 8 weeks later a normal feminine voice returned and some hair growth in the bald area was noted but other symptoms were unchanged. The tumor of the right ovary was diagnosed as a hilar cell tumor. Reinke crystalloids were numerous in the tumor tissue specimens. Normal 17-ketosteroid excretion and markedly elevated plasma testosterone appear to be characteristic of hilar cell tumors of the ovary. Estrogen levels correlated with the histology of the endometrium and urinary gonadotropin levels. The dianostic value of selective ovarian and adrenal vein catheterization was shown.