A large amount of data on the levels of 17-ketosteroids in the urine of normal and diseased persons has recently been summarized by Dorfman [1948]. It is believed that in the female the urinary 17-ketosteroids are derivatives of the steroid hormones elaborated in the adrenal cortex. In the male the testis also contributes. Isolation studies, chiefly in cases of adrenal cortical tumour and hyperplasia, have shown that the urine may also contain derivatives of the adrenal cortical hormones other than 17-ketosteroids, which may be classified as 20-ketosteroids or steroid alcohols. During the luteal phase of the menstrual cycle and in pregnancy, metabolites of progesterone, such as pregnanolones (20-ketosteroids) and 'pregnanediol', are also found in the urine. Adrenal cortical activity has recently been demonstrated in urinary extracts by biological assay, and various chemical methods have been developed for the measurement of this fraction. Increased excretions have been observed in cases of