Breast cancer is one of the most common malignancies among Korean women, with more than 7,000 new cases occurring annually. However, the mortality from breast cancer is decreasing in many western countries, despite the rising incidence, as a result of widespread screening for early detection as well as advances in the adjuvant treatment of early-stage disease. At present, the care for patients with early breast cancer has focused on minimal invasive surgery allowing the conservation of the breast and unaffected lymph nodes with a limited radiation therapy and appropriate adjuvant systemic therapy tailored to individual risk based on the tumor stage, histological grade and receptor status. It is widely accepted that the appropriate use of adjuvant systemic treatment including chemotherapy and hormone therapy improves the survival of patients with early breast cancer. The most commonly used chemotherapeutic regimen nowadays is AC (doxorubicin/cyclophosphamide). Taxane was also shown to have an advantage in adjuvant treatment of breast cancer in recent studies. It is well established that tamoxifen improves the overall survival in women with hormone receptor-positive breast cancer. Moreover, large randomized trials suggest the potential superiority of aromatase inhibitors compared to tamoxifen. Other agents, such as the monoclonal antibody against the HER-2 receptor, trastuzumab, are under investigation for clinical use as adjuvant therapy in early breast cancer. In the future, several predictive factors will be needed for better tailoring of the treatment strategy in individuals at risk. This review summarizes the current knowledge and guidelines in the management of patients with early breast cancer.