Three new isoflavonoids, named millewanins G (1) and H (2) and furowanin B (3), were isolated from the leaves of Millettia pachycarpa. Their structures were elucidated on the basis of spectroscopic analyses. The antiestrogenic activity in the yeast two-hybrid assay of these isoflavonoids was examined and shown to be comparable with that of 4-hydroxytamoxifen.