A series of novel beta-lactam containing compounds are described as antiproliferative agents and potential selective modulators of the oestrogen receptor. The purpose of the study is to evaluate the antiproliferative effects of these compounds on human MCF-7 and MDA MB-231 breast cancer cells. The compounds are designed to contain three aryl ring substituents arranged on the heterocyclic azetidin-2-one (beta-lactam), thus providing conformationally restrained analogues of the triarylethylene arrangement exemplified in the tamoxifen type structure. The compounds demonstrated potency in antiproliferative assays against MCF-7 human breast cancer cell line at low micromolar to nanomolar concentrations with low cytotoxicity and moderate binding affinity to the oestrogen receptor. The effect of a number of aryl and amine functional group substitutions on the antiproliferative activity of the beta-lactam products was explored and a brief computational structure-activity relationship investigation with molecular simulation was investigated.