This study investigated the estrogen-like activity of Adenophora triphylla var. japonica, which has been shown to have pharmacological activities. Water extracts from A. triphylla (ATWE) could bind to estrogen receptors and displaced binding of E2 to $ER{alpha}$ and $ER{eta}$. ATWE stimulated the proliferation of estrogen receptor-positive MCF-7 cells in a dose dependent manner (p<0.05). ATWE induced proliferation was blocked by the addition of the estrogen antagonist ICI 182,780 (p<0.05). Moreover, ATWE treatment caused a significant increase in mRNA expression of estrogen-responsive genes (pS2, PR, and cathepsin D; p<0.05). These results indicate that A. triphylla has estrogen-like activity and could be used to improve estrogen deficiency-related menopausal symptoms or diseases in postmenopausal women.