Mammography is a major advance and essential in the earlier detection, diagnosis and management of human carcinoma of the breast and should be more widely applied. Although mammography is at least as important as palpation and the only means of detecting nonpalpable lesions, both examinations are effective as complementary procedures. A breast operation for suspected carcinoma should never be done without preoperative mammography. Mammographic needle localization and biopsy roentgenography are useful, if not essential, in the surgical management of nonpalpable lesions.