In the last few years, ovarian ablation with GnRH agonists has been used as first-line adjuvant therapy in pre and perimenopausal breast cancer. These drugs suppress ovarian function in the hypothalamic-pituitary axis and they have adverse effects in other end-organs. A retrospective study was conducted on 35 premenopausal women, with breast cancer, and treated with goserelin, in order to investigate the effects of iatrogenic estrogen suppression. All women complaint of amenorrhea and only half of them referred hot-flashes, weight gain or arthralgias. Hot-flushes and arthralgias remit spontaneously in the end of the treatment. Osteodensitometry was used to access bone mass. There was a reduction in mineral bone mass and T-score at femoral neck and lumbar spine after the treatment with goserelin, but without statistical significance, except for the T-score in lumbar spine