The authors present the diverse etiology of nipple discharge, which background may be a tumor. They discuss the checkup ways of nipple discharge and review in detail the galactographic technique and evaluation. The examination of pathologic nipple discharge is essentially based on contact cytology, x-ray-, and ultrasound mammography. Consequently, galactography is applied by filling the ducts with contrast material. The final diagnosis is rendered by histologic examination, following the operation. The authors demonstrate the application and role of galactography through various cases.