A 23-year-old female with clinical signs of excessive androgen and estrogen production was found to have a gonadal stromal tumor. The clinical symptoms correlated well with steroid hormone values in ovarian vein blood and ovarian cyst fluid of the ovarian tumor. Ovarian vein blood draining the ovarian tumor measured as follows: estrone, 162 pg/ml; estradiol, 1688 pg/ml; progesterone, 9.6 ng/ml; testosterone, 9775 ng/100 ml; and dihydrotestosterone, 2905 ng/100 ml. The ovarian cyst fluid produced higher estrogen and lower androgen values compared with ipsilateral ovarian vein blood. Peripheral levels of immunoreactive testosterone ranged from 210 to 244 ng/100 ml. It is concluded that excessive androgen and estrogen production may arise from a gonadal stromal tumor that has been previously classified as a purely virilizing ovarian tumor.