The pharmacology of TACE (tri-p-anisylchloroethylene), a new compound with estrogenic activity, differs in important respects from that of hexestrol which is typical of the natural and better known synthetic estrogens: (1)TACE does not cause and hexestrol does cause pituitary enlargement in rats; (2) TACE has a lesser but similar effect to hexestrol on organs in which the action of the two compounds is mediated through the pituitary; (3) fat storage resulting in long activity occurs following oral administration of large doses of TACE, while there is no fat storage and action is short following hexestrol administration; (4) estrogenic material equivalent in biologic potency to more than the administered dose of TACE is eliminated with the feces, while only small amounts of estrogenic material are eliminated following hexestrol administration.