Galactography was performed in 204 women with a nipple discharge and the secretion confirmed histopathologically. All 116 intraductal tumors (papilloma, papillomatosis, carcinoma), which were associated with a serous or bloody discharge, were detected preoperatively. A palpable mass had little diagnostic significance, and exfoliative cytology was positive in only 11% (2/18) of the patients with carcinoma. The authors recommend that all patients with a spontaneous bloody or serous discharge from a single lactiferous orifice undergo galactography in addition to physical, cytological, and mammographic examination. Intraductal injection of methylene blue dye will demonstrate the affected duct system to the surgeon and can often make surgery less radical or even unnecessary.