The excretion of FSH, LH and 17-ketosteroids was studied in healthy men before, during and after administration of antiandrogens, i.e. cyproterone-acetate and cyproterone. The first compound mainly decreased the FSH-activity and to a lower extent also the LH-activity in cases with comparatively high pretreatment levels, but did not clearly affect these hormones in other subjects. The excretion of 17-ketosteroids was not much altered. In contrast the free alcohol, cyporoterone, tended to increase the FSH- and LH-levels in some, the 17-ketosteroids in all cases. The possible reasons for these effects, i.e. the dose dependency or different mode of action of the two compounds are discussed.