Xanthogranulomatous cholecystitis (XGC) is a rare inflammatory disease of the gallbladder. Not only does XGC occasionally present as a mass formation with adjacent organ invasion like a malignant neoplasm, it can also infrequently be associated with gallbladder cancer. In the situation, it is difficult to make a differential diagnosis between the diseases. Here, we describe a case of a simultaneous XGC and a carcinoma of the gallbladder in a 61-year-old woman. To the best of our knowledge, there are only a small number of reports on this combination of diseases.