The effects of admn. of various steroids on adrenal function were studied as reflected in the urinary 17-ketosteroids (17 KS) and neutral reducing lipids (NRL). Estradiol reduced 17 KS excretion, but did not affect NRL, in a single 24-year old man. In 6 women, estradiol had an inconstant effect on 17KS and no effect on NRL. In a 50-year old male castrate, estradiol reduced both 17KS and NRL. Progesterone depressed 17KS excretion in a 33-year old male. Pregnenolone reduced 17KS excretion if given intra-musc. but not orally. Testosterone increased 17KS excretion and did not affect NRL. Methyltestosterone, as a single 200 mg. intramusc. injn., failed to alter 17KS in 2 patients. Cortisone increased NRL, and had an inconstant effect on 17KS. Desoxy-corticosterone increased NRL (but not the water-soluble fraction after water-benzene partition); it did not affect 17KS.