Methylandrostenediol shared with testosterone propionate the property of protecting the renal tubular epithelium in the exptl. hydronephrotic kidney of mice. It was therefore tried in 7 women with metastatic cancer of the breast. There were 3 objective remissions and subjective sense of well-being and transitory improvement in all patients. Amts. as high as 28 g. of methylandrostenediol, given in daily doses of 100 mg. intramusc, did not cause untoward symptoms nor any of the virilizing side effects commonly seen in testosterone therapy. The compound was slightly protein anabolic, as shown in a mineral and N balance study in a patient without cancer.