Studies from our laboratory suggest that androgen excess is the endocrine abnormality that characterises women with breast cancer.To further investigate the role of androgens we did a cross-sectional study on a cohort of 592 postmenopausal breast cancer patients examining the association of circulating testosterone (T) with age, BMI and selected tumor characteristics.The most relevant findings were the significant association of high T levels with tumor size 2 cm (suggesting a role of androgens on tumor growth), and with ER positive status (suggesting that T is a marker of hormone-dependent tumors).