A 75-year-old man presented to his physician with weakness, anorexia, and constant right upper quadrant pain. He underwent a laparoscopic cholecystectomy, which was converted to an open cholecystectomy due to presumed adhesions. Direct examination of the liver was negative for masses or lesions. A CT scan was negative for masses or nodules. The gallbladder was 8.5 x 2.5 cm(2), with a diffusely thick wall measuring 2.5 cm. Microscopic examination showed a monomorphic tumor consisting of cells with increased nuclear:cytoplasmic ratio and occasional nucleoli, infiltrating the entire gallbladder uniformly. The tumor cells that reacted to antibodies directed against HepPar1, CAM 5.2, CK19 and scattered cells were immunoreactive for CD117, CD34, and CD56. This immunohistochemical profile suggested a 'hepatocellular progenitor cell tumor of the gall bladder'. This report is, to our knowledge, the first such case of a tumor of this cell type reported in the gallbladder. In addition, we present a review of the literature.