A 34-year-old woman with an adrenocortical adenoma had hypertrichosis of the extremities, abdomen and face, clitoral hypertrophy, a small uterus and amenorrhea. There was no hypertonia. Roentgenologic examination (intravenous pyelogram) showed the left kidney to be lower than normal. A pneumoretroperitoneal roentgenogram showed a suprarenal tumor on the left side. Steroid hormone metabolism was markedly disturbed. There was increased urinary excretion of 17-ketosteroids and of estrogens. The chromatographic differentiation and the absorption spectrum of the urinary 17-ketosteroids showed a predominant excretion of dehydroepiandrosterone. The ACTHstimulation test revealed no rise of the excreted 17-ketosteroids, but an increase of the excreted 17-hydroxycorticoids and estrogens. The administration of 9α-fluorohydrocortisone caused only a slight depression of the 17-ketosteroids and estrogens. No sign of an estrogen effect was found in the vaginal smears. After removal of the adrenocortical tumor, the urinary hormone levels immediately decreased to normal values. Facial hair diminished, and five weeks after operation spontaneous menstruation occurred. Since then the patient has menstruated regularly. The tumor weighed 540 grams and was examined histologically and chemically. Small amounts of aldosterone, androsterone, Δ4-androsten-3,17-dione, cortisone, dehydroepiandrosterone, estradiol, estrone and hydrocortisone were isolated from the tumor.