Historically, endocrine therapy for breast cancer began with ovarian ablation (OA) for the treatment of premenopausal patients. After the identification of estrogen receptors and the development of many antiestrogens, tamoxifen has been approved and used as the standard endocrine therapy for hormonal receptor (HR)-positive premenopausal patients to date. With the development of luteinizing hormone-releasing hormone agonists, the paradigm of endocrine therapy for premenopausal women with HR-positive breast cancer began to change from OA to ovarian function suppression (OFS). To date, the indication for OFS was limited to those premenopausal patients with HR-positive breast cancer who were unable to use tamoxifen as the primary adjuvant endocrine therapy. However, following the definitive demonstration of the therapeutic role of OFS added to tamoxifen or aromatase inhibitor after chemotherapy in large randomized trials, such as Tamoxifen and Exemestane Trial or Suppression of Ovarian Function Trial, the American Society of Clinical Oncology guidelines for the use of endocrine therapy in premenopausal HR-positive breast cancer were recently updated to recommend OFS in high-risk patients who required adjuvant chemotherapy. In contrast, the role of OFS to protect ovarian function during chemotherapy in premenopausal women has remained controversial, and some evidence showing the protective effect of OFS on the ovaries during chemotherapy as well as its therapeutic effect for breast cancer in premenopausal women with HR-negative breast cancer was recently published. Further evaluation is necessary to determine its exact role. In conclusion, the role of OA or OFS has been evolving, not only to improve the efficacy of breast cancer treatment, but also to preserve ovary function. OFS remains a main strategy for premenopausal women with HR-positive early breast cancer, though its exact role should be determined in further studies.