Extramedullary plasmacytoma of the gallbladder is extremely rare. A review of the literature in English revealed only one case, involving a patient with initial extramedullary plasmacytoma of the maxillary sinus. In this report, we describe the case of a 63-year-old man with surgically confirmed extramedullary plasmacytoma confined to the gallbladder. At ultrasonography and computed tomography, diffuse and uniform thickening of the gallbladder wall without evidence of surrounding tissue infiltration was depicted.