A rare case of primary gallbladder carcinoma is reported. A 67 year-old woman was admitted to our hospital for treatment of suspected duodenal carcinoma. A series of radiographic examinations demonstrated a giant tumor involving the duodenum, gallbladder, pancreatic head, and transverse colon. These extensions made it difficult to identify the primary origin of the carcinoma. Pancreatoduodenectomy, cholecystectomy, and resection of the transverse colon were performed. Macroscopically, ulcerative lesions were seen in both the gallbladder and the duodenum. Microscopic examination revealed adenosquamous cell carcinoma of the gallbladder, invasive of the adjacent organs, including circumferential invasion of the second portion of the duodenum. The patient tolerated the operation well and was discharged 28 days post-operatively, but died of liver metastasis 4 months after surgery. Local invasion of the surrounding tissues is characteristic of adenosquamous/squamous cell carcinoma of the gallbladder. Although surgery for cure is deemed possible, the rapid growth rate of this type of tumor may cast doubt on the value of extensive radical surgery.