To recognize the new entity-intraductal papillary neoplasia of bile duct in liver, the authors reviewed the clinical records of sixteen patients, analyzed the microscopic features, and selected immunohistochemical reactivity (cytokeratins and mucins) that might correlate with classification. Ten patients were male and six were female, with a mean age of 58 years (range, 21-73 years). According to their cell phenotypes, these papillary tumors were classified as intestinal type (6 cases), pancratobiliary type (4 cases), gastric type (5 cases) and oncocytic type (1 case). Most were located in the left hepatic duct and accompanied with bile duct dilatation (10 cases). Eight showed minimal expansile invasion into the ductal wall and eight were noninvasive. Five patients were treated with a hepatectomy, three underwent segmental resections, and one underwent a left hepatic lobectomy. One patient died of unrelated causes 6 years after operation, and another died of postoperative complications. The remaining 7 patients are alive and disease free 1-5 years after surgery. Because of its distinct clinical, pathological features and a favorable prognosis can be expected after complete surgical resection, we suggested that intraductal papillary neoplasia should be distinguished from other types of peripheral cholangiocarcinoma, as a distinct entity, like its counterparts in the pancreas. Neoexpressed and overexpressed mucins are of clinical value as a marker for supportive diagnosis, prognosis or monitoring therapy.