Traditional prognostic markers in breast cancer include histological variables such as tumor size, grade, and axillary node status. In recent years some new potential prognostic markers of a biochemical nature have been described: estradiol receptors, progesterone receptors, epidermal growth factor receptors, erbB-2 proto-oncogene, and certain proteolytic enzymes. None of these new markers excels axillary node status as a prognostic marker. Biochemical markers can, however, be evaluated with use of minimal surgery and may help distinguish the minority of aggressive axillary-node-negative breast cancers.