The evaluation of menopausal status is an important subject in the field of treatment of hormone receptor positive breast cancer. According to the menopausal status, endocrine therapy should be categorized by individual patient. However, the gonadal injury caused by various therapeutic drugs and its recovery would confuse the interpretation of clinical and biological markers for ovarian reserve. There are some methods to examine the functional ovarian reserve indirectly. Ultrasonography for counting follicles is a relatively reliable procedure, although it is not feasible because of time-labor consumption and high cost. Biological marker from blood samples such as serum follicle stimulating hormone (FSH), serum estradiol (E2), serum inhibin, or anti-Müllerian hormone (AMH) would be a better choice. The examination of serum FSH and E2 is already recommended as biomarkers for measuring functional ovarian reserve in many guidelines. However, there are limitation of serum FSH and E2 in patients with chemotherapy-induced amenorrhea and treated by tamoxifen. AMH is promising biomarker in the field of infertility treatment even in the patients treated by chemotherapy. It might be a possible biomarker to determine the menopausal status for decision-making whether aromatase inhibitor could be applicable or not in hormone positive breast cancer patients with chemotherapy induced amenorrhea or treated by tamoxifen.