Xanthogranulomatous cholecystitis (XGC) is an unusual and destructive inflammatory process that is characterized by thickening of the gallbladder (GB) wall with a tendency to adhere to neighboring organs. XGC is often mistaken for GB carcinoma, and the frequency of the coexistence of these two lesions is approximately 10%. Therefore, in case of severe XGC, there is chance of either overlooking the carcinoma or other significant lesions. CA 19-9 is commonly measured in the serum of patients with hepatobiliary malignancies. Although CA 19-9 can be elevated in benign conditions such as cholestasis, pancreatitis, tuberculosis, thyroid disease etc., malignancy should be considered at first in setting of its significant and persistent elevation. We report a case of a 62-year-old man who showed continuously rising level of CA19-9 over 2000 U/mL after cholecystectomy for xanthogranulomatous cholecystitis and finally was diagnosed as cholangiocarcinoma by short-term follow up. (Korean J Gastroenterol 2010;55:404-409)