The term ductal papilloma is used to identify a group of 3 rare benign papillary salivary gland tumors known as inverted ductal papilloma, sialadenoma papilliferum, and intraductal papilloma. They represent adenomas with unique papillary features and arise from the salivary gland duct system. We describe the clinical and microscopic features of 19 new cases of ductal papillomas and combine them with 116 cases previously published in the English-language medical literature. These 19 cases were composed of 13 inverted ductal papillomas, 3 sialadenoma papilliferums, and 3 intraductal papillomas. Collectively, these 19 ductal papillomas occurred most commonly in the sixth to eighth decade of life, with an average patient age of 54 years. Men predominated 1.37:1. The sialadenoma papilliferums presented as papillary lesions clinically with all 3 misinterpreted as squamous papillomas by the surgeons. The inverted ductal papillomas and intraductal papillomas appeared as submucosal nodules. The lip and the palate were the most common locations for inverted ductal papilloma and sialadenoma papilliferum, respectively. The sites for the 3 intraductal papillomas were the parotid papilla of the Stensen's duct, the upper lip, and the buccal mucosa. With light microscopy, inverted ductal papillomas appeared to arise from the excretory ducts near the mucosal surface, whereas intraductal papillomas appeared to arise from the excretory ducts at a deeper level. Sialadenoma papilliferum had a more complex histology, with a biphasic growth pattern of exophytic papillary and endophytic components. All 19 cases were treated by surgical excision. Follow-up information was available in only 2 cases, both inverted ductal papillomas. Neither case recurred during a 20-year period. Sialadenoma papilliferum, with a literature-derived recurrence rate of 10% to 15%, seems to assert a more significant biological behavior than inverted ductal papilloma and intraductal papilloma. Our findings justify the separation of these 3 entities based on clinical and histologic parameters. They are tumors of adulthood and, in addition, have in common their relationship to the excretory duct system, their anatomical distribution, and their general behavior.