Adjuvant therapy of breast cancer is accepted as a useful method for reducing mortality in patients with histologically axillary involved lymph nodes. Polychemotherapy regimens and hormonal treatment procedures are used to reach this goal. Hormonal treatment seems to be useful especially in selected patients. This article deals with (a) new methods for selecting hormone-responsive tumors and patients, and (b) it will give a brief overview of major publications concerning adjuvant endocrine therapy and (c) will summarize the data from the Gynecological Adjuvant Breast Group (GABG) trials.