AIM: To observe the therapeutic action of Guizhifuling Capsule (Ramuluo Cinnamomi, Poria, Cortex moutan, Semen Persicae, etc.)on hyperplasia of mammary glands in rast, and to explore the new therapeutic effectiveness and its mechanism. METHODS: To inject extrinsic E2 and Pt into muscle to reproduce rats model of hyperplasia of mammary glands, to observe the morphologic changes of nipple in every group, determine extradiol and progesterone content on plasma in experimental rats by radio immunoassay, and study the changes of ER and PR by immunohistochemical method. RESULTS: Compared with the model group, Guizhi Fuling Capsule can markedly abate papilledema, proliferation of lobule, acinus and duct in mammary glands, reduce obviously changes of blood, estradiol on plasma, the ER and PR content of mammary glands and increase progesterone. CONCLUSION:Cuizhi Fuling Capsules have the good therapeutic action on hyperplasia of mammary glands in rats, its mechanism is related to correcting changes of blood, adjusting the blood concentration of sexual hormone in experimental rats and its expression of receptor.