Objective: Mammary ductoscopy allows direct visualization of the ductal system and a method for directed excision and pathologic diagnosis. We reviewed our experience with mammary ductoscopy in the evaluation of pathologic nipple discharge. Methods: We reviewed all patients who underwent ductoscopy for pathologic nipple discharge at our institution from 2006-2010. All procedures were performed by a single surgeon. Data included patient and imaging characteristics, indications, operative findings, and pathologic outcomes. Descriptive statistics were used for data summary. Results: During the study period, 121 patients underwent ductoscopy and directed duct excision for pathologic nipple discharge, including 66 (55%) with bloody discharge. Breast imaging [mammography, ultrasound, and/or magnetic resonance imaging (MRI)] revealed BIRADS category I/II/III findings in 112 (93%), BIRADS category IV findings in 6 (5%), and was unknown in 3 (2%) patients. Final pathology revealed papillomas in 64 (53%) patients, duct ectasia and associated benign findings in 48 (40%) patients, ductal carcinoma in situ (DCIS) in 7 (6%) patients, and atypical ductal hyperplasia in 2 (1%) patients. None of the patients with DCIS underwent preductoscopy MRI, but all had BIRADS category I/II/III breast imaging. The extent of DCIS identified by ductoscopy and subsequent surgical excision ranged from <;1 cm to 10 cm (median 3 cm). Conclusions. The majority of patients with pathologic nipple discharge have benign nonproliferative findings or benign papillomas. Although atypia and malignancy were diagnosed in only 7% of patients who underwent ductoscopy for pathologic nipple discharge, there were no routine imaging findings indicative of these diagnoses preoperatively.