74 cases with discharge from the breasts were treated surgically by pyramidectomy and histology. The histology was studied. The causes were: 1) ectasia (55%), 2) papilloma (30%) and 3), much more rare, cancer (8%). A blood-stained discharge (31 cases, 42%) could be due to these three causes, but the 4 cancers and the 2 borderline lesions belonged to the group of blood-stained discharges. A serious discharge (17 cases, 23%) could be due to ectasia or a papilloma. A thick discharge (16 cases, 21.5%) is always due to ectasia. The lactiferous duct is treated clinically and using X-rays to outline it. X-ray diagnostic methods and cytology are used in making the diagnosis. Clusters of papillae show that there is intra-canular proliferation. The literature is reviewed and a scheme of treatment is outlined.