A series of gem -dichlorocyclopropyl and cyclopropyl analogs of stilbene congeners was synthesized and examined for estrogenic and antiestrogenic activity using the uterotropic assay in the immature mouse. The relative receptor affinity in vitro was determined by measuring [3H]estradiol displacement from the rat uterine cytosol receptor. The 11 test compounds synthesized in this study did not produce estrogenic or antiestrogenic activity at the dosage levels used (1–25 μg), but did produce a significant displacement of [3H]estradiol in the rat uterine receptor binding assay with analog XVIII possessing the greatest binding affinity and compound XI the lowest affinity. Structure-affinity relationships of this series were established from the receptor binding assay and comparisons between these analogs and a previously reported series are summarized.