Abstract:Objective: Research on the phytoestrogenic effect and its possible mechanism of formononetin. Method: To evaluate the estrogenic effect and mechanisms of formononetin through the test of its influence on proliferation and ER subtype expression of T47D cells. Result: The proliferation rates of T47D cells treated with 1×10-7-1×10-6 mol·L-1 formononetin were not increased. On the influence of ICI182, 780, the proliferation rates of T47D cells treated with 1×10-7 - 1×10-6mol·L-1 formononetin were decreased. Formonenetin could induce the augment of ERα expression significantly of T47D. Conclusion: Formonenetin has phytoestrogenic effect. Formonenetin can not accelerate ER(+) T47D cell proliferation. But the expression level of ERα subtype in T47D cells change significantly with certain concentrations of formonenetin.