We report a case of xanthogranulomatous cholecystitis (XGC) showing high levels of serum DUPAN-II in a 65-year-old woman. Preoperative radiologic examination showed no abnormal findings except in the gallbladder. Endoscopic ultrasonography was effective for differentiating chronic cholecystitis from gallbladder cancer before the operation. Cholecystectomy was performed by laparotomy, and the diagnosis of XGC was confirmed intraoperatively by examining a frozen section. Histologically, no cancer lesion was observed in the gallbladder, while immunochemical reactivity to DUPAN-II was demonstrated in the brush-border area of the epithelium and in histiocytes in the gallbladder. The half-life of serum DUPAN-II in our patient after cholecystectomy was approximately 1 month, and finally dropped to within the normal range after cholecystectomy.