A method for preventing, diagnosing, or treating a condition mediated by an estrogen receptor by administering to a patient in need thereof an effective amount of a compound of formula I, II, or a combination thereof: wherein R1, R3, R4, and R5 are independently selected from H, OH, and OR.sub.a; R2 is selected from H, OH, and (C.dbd.O)(C.sub.1-7)alkyl; R.sub.a is (C.sub.1-7)alkyl or (C.dbd.O)(C.sub.1-7)alkyl; or a derivative of the compound selected from N-oxide derivatives, prodrug derivatives, protected derivatives, isomers, and mixtures of isomers of the compound; or a pharmaceutically acceptable salt or solvate of the compound or the derivative. Compounds of formula I and II and pharmaceuticals compositions thereof are also presented. ##STR00001##