This chapter covers issues most likely to be raised by young women who have been diagnosed with breast cancer or those at high risk of the disease contemplating assisted fertility procedures. The type of adjuvant regimen selected for an individual woman is determined by menopause status, biological characteristics of the tumor and risk of relapse. Large meta-analyses of multiple trials with longterm follow-up have been used to assess the effects of systemic therapy on breast cancer outcomes. Achievement of amenorrhea appears to be associated with a reduction in relapse and improvement in survival in premenopausal women with estrogen receptor positive (ER+) tumors. There are three main barriers to implementing fertility preservation in women with breast cancer: cost; concern about treatment delays; and concern that increasing sex hormones as a result of controlled ovarian stimulation (COS) protocols will stimulate proliferation in ER+ tumors.