Estrogen like activities were evaluated using ethanol and hot water extracts of herbal medicines by using an in vitro detection system. Bokryung (Poria cocos), Sanyak (root of Dioscorea batatas) and Mokdanpi (root skin of Paeonia suffruticosa) represented statistically significant estrogen-like activities (p<0.001), while Omija (fruit of Schizandra chinensis), Taeksa (root of Alisma canaliculatum A. BR.), Jihwang (root of Rhemannia glutinosa), and Sansuyu (fruit of Cornus officinalis) did not. Estrogen-like activities of Bokryung hot water extract (500 ${mu}g/ml$) and ethanol extract (50 ${mu}g/ml$) were almost same as that of a C M $17{eta}$-estradiol. Furthermore, estrogen-like activities of ethanol extracts (500 ${mu}g/ml$) of Bokryung and Mokdanpi were stronger than that of $10^{-7}$ M $17{eta}$-estradiol. These results suggest that Bokryung, Sanyak and Mokdanpi show estrogen-like activities. Especially, Sanyak and Mokdanpi represented promotive effect on the proliferation of MC3T3-E1 osteoblastic cells. Bokryung, Sanyak and Mokdanpi also exhibited superior inhibitory effect on the viability of RAW 264.7 cells. In conclusion, these three herbal medicines might be interpreted as candidates for the further study or development of functional foods or medicine to prevent or avoid postmenopausal symptoms of women.