The role of axillary lymph node dissection in breast cancer patients has long been the subject of controversial discussion. The reason for this is that the removal of axillary lymph nodes is associated with high morbidity and is of little value for long-time prognosis. With the introduction of sentinel node biopsy, a new minimal invasive procedure is now at the stage of clinical evaluation. This new technique seems to predict axillary status with high accuracy by removal of a single representative lymph node. Patients with negative axillary status might be spared complete axillary dissection. Due to a number of unsolved technical details and a remarkable learning curve for individual surgeons, sentinel node biopsy should not be introduced as a clinical standard before questions of patient selection, training, and quality control have been solved.