OBJECTIVE: To observe the effect of acupuncture combined with medication (Rule Granule) on serum prolactin (PRL)，estradiol (E2) and progestone (P) contents and expressions of prolactin receptor (PRLR), estrogen receptor (ER) and progestrone receptor (PR) proteins in mammary gland (MG) tissues of MG hyperplasia (MGH) rats, so as to explore its mechanisms underlying improvement of MGH. METHODS: A total of 55 female SD rats were randomized into blank control group (n＝10), model group (n＝10), acupuncture group (n＝11), medication group (n＝10), and acupuncture plus medication group (n＝9). The MGH model was established by muscular injection of E2 benzoate(0.5 mg/kg, once daily for 20 days), followed by injection of P (5 mg/kg) into the lateral muscle of the hind-limb, once daily for 5 days, and the rats of the control group were treated by muscular injection of normal saline at the same site and in the same procedures. Acupoint group A composed of bilateral Tianzhong (SI 11), Ganshu (BL 18) and Zusanli (ST 36), and group B composed of Tanzhong (CV 17), and bilateral Wuyi (ST 15) and Hegu (LI 4) were alternatively punctured with filiform needles and stimulated swiftly by twirling the needle in each acupoint for 20－30 sec, once daily for 30 days. Rats of the medication group and acupuncture ＋medication group were treated by gavage of Rule Granule fluid containing Baishao (Paeonia Iactiflora Pall), Danggui (Angelica sinensis), etc. (1.5 mL/100 g for each rat) and those of the other groups treated by gavage of distilled water (1.5 mL/100 g). The treatment was given once daily for continuous 30 d. At the end of the experiments, the rats' abdominal aorta blood was collected for assaying the contents of serum PRL, E2 and P with ELISA, and the pathological changes of breast tissue (the left 2nd pairs) were observed under microscope after sectioning and H．E. staining. The expression of PRLR, ER and PR proteins in the breast tissue was detected by immunohistochemistry. RESULTS: After modeling, the hyperplasia of mammary gland in the model group was obvious; the serum PRL and E2 contents and the immunoactivities of PRLR, ER and PR were significantly increased (P<0.01); and the content of serum P was considerably decreased in the model group in comparison with the blank control group (P<0.01). After the treatment, the hyperplasia of mammary gland was improved; the serum PRL and E2 contents and the expression of PRLR, ER and PR were significantly decreased (P<0.05, P<0.01); and the content of P was notably increased in the acupuncture, medication and acupuncture plus medication groups relevant to the model group (P<0.05，P<0.01). The therapeutic effects of acupuncture plus medication were significantly superior to those of both simple medication and simple acupuncture in down-regulating serum PRL and E2 contents and PRLR, ER and PR immunoactivity, as well as in up-regulating serum P content (P<0.05). No significant differences were found between the medication and acupuncture groups in the above mentioned 3 serum and 3 mammary indexes (P>0.05)．. CONCLUSION: Acupuncture, Rule Granule, and acupuncture combined with Rule Granule can improve hyperplasia of mammary gland in rats, which may be related to their effects in reducing serum PRL and E2 and breast ER, PR and PRLR expression levels, and in increasing serum P level. The therapeutic effects of acupuncture plus Rule Granule are better than those of simple acupuncture and simple Rule Granule.