Abstract: The study was designed to test the estrogen-like effects about allantoin. The activity of the allantoin was investigated by mouse uterine weight gain test and MCF-7 cell proliferation assay. The levels of E2, FSH and LH were also measured. ICI182,780, MPP, THC and G15 antagonnist assay and Western blot were adopted to explore the mechanism of allantoin. Allantoin increased the uterus index of premature female mice, the levels of E2 and FSH, and the expression of ERα and GPR30, compared with the control group. Allantoin also promoted the proliferation of MCF-7 cells. Co-incubation of MCF-7 cells with estrogen receptor blockers, ICI182,780, MPP and G15 abolished the inductive effect of the proliferation. These results suggest that allantoin has estrogenic activities, which are mainly mediated by ERα, GPR30.