The effect of various dosages of ethinyl estradiol or diethylstilbestrol on sebaceous gland secretion was studied in 54 women, 15 of whom had acne. A significant decrease in sebum production was observed with all doses studied except for 0.02 mg of ethinyl estradiol. The maximum suppressive effect in terms of the percent reduction of sebum was seen with the highest doses, 33.7% for ethinyl estradiol (0.25 mg daily) and 35.4% for diethylstilbestrol (5.0 mg daily). However, for any given dosage of either estrogen, there were marked differences in sebaceous gland responsiveness from individual to individual. There was a significantly positive correlation between the degree of sebaceous gland inhibition and acne improvement.