OBJECTIVE：To study the effects and mechanism of Compound lujiao rutongning capsule on rats with mammary glands hyperplasia. METHODS：120 rats were randomly divided into normal group，model group，tamoxifen group （positive drug，1.8 mg/kg）and Compound lujiao rutongning capsule low-dose，middle-dose and high-dose groups（70，140，280 mg/kg）. The model of mammary gland hyperplasia was induced by injecting benzoate estradiol and progesterone except normal group. After modeling，they were given relevant medicines intragastrically，and normal group and model group were given isometric distilled water intragastrically once a day. The effects of Compound lujiao rutongning capsule on the diameters of nipple in rats were observed after 30 d. The levels of PRL，FSH，E2，LH and progesterone in serum of rats were all determined，and morphology of breast tissue was observed. RESULTS：Compared with before modeling，the diameters of nipple in rats increased before medication and after modeling （P＜0.05）. After medication，compared with model group，the diameters of nipple in rats decreased in treatment groups，and the serum levels of PRL，FSH and E2 in Compound lujiao rutongning capsule medium-dose and high-dose groups decreased， while the levels of LH and progesterone increased；the level of FSH in Compound lujiao rutongning capsule low-dose group increased，while the level of progesterone decreased（P＜0.05）. Breast tissue lesions of rats relieved to different extent，the number of lobuli mammae and acinus and the layer of duct epithelial decreased to different extent（P＜0.05），and morphology of breast tissue had been improved. The effect of Compound lujiao rutongning capsule was equal to positive drug. CONCLUSIONS： Compound lujiao rutongning capsule could ameliorate mammary glands hyperplasia of rats，and its mechanism may be associated with the down-regulation of PRL，FSH and E2 and the up-regulation of LH and progesterone.