Abstract We report here the synthesis and cell-proliferation properties of derivatives of the breast cancer drug tamoxifen, in which the [BOND] O (CH 2) 2 N (CH 3) 2 side chain, responsible for the drug's antiestrogenic properties, has been modified by a ferrocenyl moiety. We recently reported the diphenol compound 5, in which this amino chain had been replaced with an acyl-ferrocenyl ([BOND] O (CH 2) 2 C (O)[(η 5-C 5 H 4) FeCp]) group, ...