It seems that the principal antiandrogenic action of cyproterone acetate is on the site of the androgenic receptors. Since recent work proves that there is an action on plasma testosterone, we wanted to check in women with raised testosterone levels if cyproterone lowered these levels. The answer is : Yes. Observations seem to confirm that cyproterone acetate causes a significant lowering of plasma testosterone. The basic level of testosterone and the drop in blood levels of testosterone after the antiandrogenic action has occurring do not seem to be significantly different whether the virilism is caused by an adrenal mechanism or by an ovarian mechanism.