Androgenic granulosa cell tumors of the ovary are rare and have not been well studied hormonally. A 20-year-old woman complaining of secondary amenorrhea with high plasma testosterone (295 ng/dl) and a right ovarian tumor was studied. Plasma testosterone levels decreased after two days of dexamethasone (36 ng/dl), increased after hCG administration (538 ng/dl) and a unilateral right ovarian gradient of testosterone was noted at the selective catheterization of ovarian veins. After removal of the granulosa cell tumor, testosterone concentration returned to normal (68 ng/dl) and the patient had resumption of normal menses.