Nearly one third of women diagnosed with invasive breast cancer are younger than 50 years with regular menstrual cycles. 60% of these tumors express estrogene and progesterone receptors. Common treatment procedure is surgery followed by chemotherapy, radiotherapy and hormone therapy. Often in younger patients chemotherapy causes permanent amenorrhoea. In case that menses afterwards occurs ovarial suppression is needed, mostly by goserelin, LH-RH agonist. The principle of therapy is to cause inhibition of LH and FSH pituitary secretion (medicamental ovariectomy). Sometimes in premenopausal women ovarian suppression is added to standard chemohormonal therapy. In this review two high-risk node positive premenopause breast cancer patients are presented, diagnosed at the age of 38 and 28. Both had hormone receptors positive tumor and underwent breast surgery followed by FEC regimen chemotherapy and radiotherapy. Chemotherapy caused them temporary amenorrhoea, but soon after radiotherapy and tamoxifen introduction regular menstrual cycle began. Due to high-risk node positive cancer combined therapy with tamoxifen 20 mg daily and goserelin 3,6 mg S.C. monthly was introduced. The first patient needed a three months goserelin application to obtain amenorrhoea but the other patient needed only one. After six months of goserelin plus tamoxifen therapy gynaecological and endocrinological evaluation was preformed. In both patients LH value was lower than 1.0 IJ/L but in the first one FSH, estradiole and progesterone values were within menopausal ranges with ultrasound proof of ovarial and endometrial inactivity. In the other patient FSH, estradiole and progesterone values were within fertile range, with present ovary follicles, although ammenorrhoic. This review refered that numerous individual factors influence the effect of adiuvant LH-RH agonist therapy in high-risk breast cancer patient and that different time period is needed to obtain its maximum effect.