Approximately 25% of breast cancers occur in women under age 50 and 800 cases each year in Australia occur in women younger than 40. Most of these young women receive chemotherapy as part of their treatment. Early menopause and associated infertility are important potential side-effects of chemotherapy for breast cancer. Risk is associated with age, and type and cumulative dose of chemotherapy. Desire for future pregnancy should be discussed with all premenopausal women with newly diagnosed, potentially curable breast cancer. Early referral to a fertility specialist is important for those who wish to preserve fertility so that options such as embryo or oocyte cryopreservation can be offered. A recent international randomised clinical trial of 257 premenopausal women with operable hormone-receptor negative breast cancer has shown that use of the GnRH agonist, goserelin (Zoladex) given during chemotherapy reduces risk of chemotherapy-induced menopause by 70% with an ovarian failure rate at 2 years of 8% in the goserelin group and 22% in the chemotherapy-alone group (odds ratio, 0.30; 95% confidence interval, 0.09 to 0.97; two-sided P = 0.04). Pregnancy occurred in more women in the goserelin group than in the chemotherapy-alone group (21% vs. 11%, P = 0.03). Use of goserelin during chemotherapy did not adversely impact disease outcomes; 4 year disease-free survival 92% for the goserelin group vs 82% for the chemotherapy-alone group, adjusted HR 0.43; 95% CI, 0.18 to 1.00; P = 0.05. Premenopausal women, beginning curative intent chemotherapy for BC should consider use of GnRH agonist during chemotherapy, starting at least 1 week before chemotherapy, to prevent chemotherapy-induced menopause. Where available it is also important to offer other proven interventions such as cryopreservation of embryos or oocytes.