Four hundred and ten women with serous or bleeding nipple discharge without palpable mass were treated by surgery in the Curie Institute between 1970 and 1984. The cancer rate in this group was 12.2 per cent. Galactography was of anatomical interest as it showed the canal at the origin of the discharge. Malignant cells were observed at cytological examination in only 17 per cent of intragalactophoric cancers. Surgical excision is necessary if the nipple discharge is uniporous and easily reproducible by areolar pressure, particularly in the post-menopausal period when the frequency of cancer is highest (17.7 per cent).