Five hydroxylated analogues of tamoxifen [1, (Z)-2-[p-(1,2-diphenyl-1-butenyl)phenoxy]-N,N-dimethylethylamine] and its geometric isomer were prepared by reaction of protected hydroxy-alpha-ethyldeoxybenzoins with 4-[2-dimethylamino) ethoxy]phenylmagnesium bromide, followed by acid-catalyzed dehydration-deprotection and chromatographic separation of isomer mixtures. Estrogen receptor binding affinity and estrogenic and antiestrogenic activity of each of the compounds were determined in the rat, in comparison with 4-hydroxytamoxifen (2). The new compounds had a wide range of receptor binding affinities, with that of 3-hydroxytamoxifen (6c), the most strongly bound, approaching that of estradiol. The trans isomers 6a,b were more strongly bound than were the cis isomers 7a,b. Antiestrogenic activity was seen in all compounds except 7b. This was also true for estrogenic activity, except that in 6c this activity was also substantially reduced. Maximal antiestrogenic effectiveness of 6c occurred at a 10-fold greater daily dose (50 micrograms/rat) than that required for maximal effect of 2.