BACKGROUND This study examined the effect of kaempferol on uterine fibroids in vitro and the underlying mechanism, and investigated the potential of kaempferol as a clinical drug for the treatment of uterine fibroids. MATERIAL AND METHODS Uterine fibroid tissue and surrounding smooth muscle tissue were collected for primary culture. Different concentrations of kaempferol (12 μM, 24 μM, and 48 μM) were used to treat the cells for 24, 48, and 72 hours. Ethanol was used in the control group. A CCK-8 colorimetric assay was used to detect cell proliferation. Real-time PCR and immunoblot were used to detect estrogen receptor (ER), insulin-like growth factor-1 (IGF-1), and vascular endothelial growth factor (VEGF) levels in mRNA and protein. RESULTS The differences in proliferation at different time points and concentrations of kaempferol were statistically significant. The inhibitory effect of kaempferol on mRNA levels of ER and IGF, and protein levels of ER, VEGF, and IGF-1 were positively correlated with kaempferol concentration. Changes in kaempferol concentration showed no effect on VEGF mRNA expression. Treatment with kaempferol significantly lowered myocardin levels in uterine fibroid tissue compared to normal uterine smooth muscle (P<0.05). CONCLUSIONS Kaempferol might be used for clinical treatment of uterine fibroids due to its inhibitory effect on the proliferation of uterine fibroids cells.