Nipple discharge is a common breast symptom. While it can be a source of significant anxiety and concern, most nipple discharge is due to benign etiologies, including medication side effects, duct ectasia, pregnancy, and repeated manipulation of the breasts or nipples. Less common pathologic causes include papilloma, ductal carcinoma in situ (DCIS), invasive cancer, mastitis, and/or abscess. Galactorrhea refers to milky discharge in patients who are not pregnant or breastfeeding and is usually related to elevated levels of prolactin. The workup of nipple discharge includes a medical history, comprehensive physical examination, breast imaging, and sometimes biopsy and/or surgery.