Abstract: Objective To investigate the association between serum sex hormone levels as well as body mass index and breast cancer in postmenopausal women.Methods We selected the cases of postmenopausal women who accepted surgical treatment for the first time which from March 2013 to December 2013 in the department of breast surgery the Affiliated Tumor Hospital of Harbin Medical University,of which 118 cases of patients with breast cancer and 60 cases of benign breast lesions as control group.Meanwhile,information of body height and weight.were collected.Serum estradiol(E2),estrone(E1),testosterone(TSTO)and androstenedione(AED)concentrations were measured in 118 postmenopausal women with breast cancer patients and 60 matched control subjects by enzyme-linked immunosorbent assay(ELISA),then the results were estimated.Results The levels of serum E2,E1,AED of breast cancer group were significantly higher than those in control group(P＜0.05).The serum level of TSTO in cases group was higher than the control group,but the results were not statistically significant(P＞0.05).The levels of body mass index(BMI)were not statistically significant(P＞0.05)between breast cancer group and the control group.The level of E1 in breast cancer group and levels of E1,TSTO,AED in overall of overweight group were significantly higher in overweight(P＜0.05),yet we have not found association between levels of hormone and BMI.Conclusion The level of serum sex hormones is higher with breast cancer in postmenopausal women,while high serum levels of E2,E1,AED maybe associated with breast cancer in postmenopausal women.Sex hormones are higher in postmenopausal women with high BMI.