ObjectiveTo investigate the features of common bile duct adenoma under endoscopic ultrasonography (EUS). MethodsClinical data of 15 patients with common bile duct adenomas confirmed by pathology from January 2015 to January 2020 in Tianjin Nankai Hospital were analyzed retrospectively. The patients′ EUS features were summarized. ResultsThe common bile duct adenoma was characterized by homogeneous soft tissue mass with medium or low echo and clear boundary, floating in the bile duct with no movement under EUS. EUS diagnosis of 14 out of 15 patients was consitent with the pathology, and the diagnostic consistency was 93.3%. One patient with a movable lesion was misdiagnosed as cholestasis by EUS. One patient had two solitary adenomas, located in the middle and lower part of the common bile duct, and 14 others had single adenoma. There were 9 adenomas in the lower part, 4 in the ampulla, 2 in the upper part, and 1 in the middle of the common bile duct. The pathological findings were 7 cases of villous adenoma with high-grade intraepithelial neoplasia, 4 cases of local malignant changes; 6 villous tubular adenoma with high-grade intraepithelial neoplasia, 3 local malignant changes; 2 villous tubular adenoma with low-grade intraepithelial neoplasia; and 1 papillary adenoma. ConclusionEUS, helpful for the qualitative diagnosis, can be used as an important technique to improve the diagnosis of common bile duct adenoma.