The majority of breast diseases result from lesions of the ductal epithelium. Mammary ductoscopy allows for visualization of intraductal abnormalities, and ductoscopic lavage provides thousands of cells for analysis. We reviewed our experience of 89 cases of patients with pathologic nipple discharge (PND) undergoing ductoscopy-directed duct excision and collection of ductal washings. Patients undergoing ductoscopy-directed duct excision with ductal washings had an 88% abnormal pathology rate. Most abnormalities were benign (71% papillomas), but the atypia rate for this group was 62%. The combination of visualization and pathologic analysis of washings provided the highest predictive value for the diagnosis of papilloma. Cellular yields for this technique were excellent with most specimens yielding >5,000 epithelial cells per high powered field and with evaluable ductal cells in 82% of specimens. Mammary ductoscopy offers the advantage of a high lesion localization rates with intraoperative guidance. The most accurate tool was the combination of ductal washings and ductoscopic visualization, but preoperative use of these techniques is not helpful in most cases. Greater than 90% of patients with PND are found to have a lesion on pathologic examination when using this technique for directed duct excision. Of interest, ductal washings obtained from symptomatic patients with benign diseases are often atypical.