PURPOSE: This study was designed to assess the CT findings of a juxtapapillary duodenal diverticulum (JPDD) and to determine if there is an association between a JPDD and biliary disease using MDCT multiplanar reformation (MPR). In addition, a study was performed to determine if MPR is more useful than an axial image only for an analysis of duodenal diverticula. MATERIALS AND METHODS: A total of 49 patients who had JPDD as identified on an MDCT image were retrospectively included in this study. Patients were divided into two groups: patients with biliary disease (Group 1) and patents without biliary disease (Group 2). A total of 23 patients (46.9%) had biliary disease. We analyzed the size, location, content of the diverticulum, compression of the biliary duct by a diverticulum and the site of a duodenal papilla with an axial image only and MPR images. RESULTS: The frequency of biliary disease was increased when the papilla was located inside a diverticulum (p = 0.033). The use of an MPR image was more useful than an axial image alone for the evaluation of a site of a duodenal papilla. CONCLUSION: A JPDD is associated with the development of biliary disease and the risk of biliary disease is increased when the papilla is located in a diverticulum. An MPR image can provide more precise information about the site of a papilla than an axial image for the evaluation of a JPDD.