Changes in the breast begin at the time of puberty because of the cyclical influence of ovarian hormones. This intermittent stimulation usually results in some nodularity of the breast by the time a woman reaches 30 and frequently at an earlier age. The real importance of fibrocystic disease is related to the problem of differential diagnosis of benign from malignant lumps. Mammography has become the standard method for detecting lumps in the early, nonpalpable stage, but refinements in thermography, ultrasound, and CT scanning may become more useful. Considerable work is apparently being done on various chemical markers, but at the present time, they are not sufficiently reliable for routine clinical use. Fine needle aspiration biopsy with cytologic analysis has become more popular as a detection method, and core needle biopsies with histology are sometimes used. Analysis of nipple secretions for chemical markers or for cytologic diagnosis may become more reliable. A combination of factors will probably give the best results, at least in the foreseeable future, and the judgment of an informed and skilled examiner will remain the best method for the detection of early breast cancer for many years to come.