ANTIANDBOGBNS are substances which prevent androgens from expressing their activity at target sites. The inhibitory effect of these substances, therefore, would be differentiated from compounds which decrease the synthesis and/or release of hypothalamic (releasing factors) and anterior pituitary hormones (gonadotrophins, particularly luteinizing hormone) and materials which act directly on the gonads to inhibit biosynthesis and/or secretion of androgens.Substances possessing antiandrogenic activity are of practical as well as theoretical interest. Systemically active compounds of this class would be expected to benefit women suffering from certain types of hirsutism and men suffering from androgendependentprostatic tumors or benign prostatic hypertrophy. Local use of antiandrogenic compounds also could be of use in women with hypertrichosis, in prevention of certain types of male baldness, for the inhibition of facial hair growth in men, and for the treatment and/or prevention of acne in young men and women.This communication will be concerned with the biology of antiandrogens, particularly from the viewpoint of bioassay models that are available for prediction of useful therapeutic activity on human skin.