A patient with a primary gastric carcinoma complicated with a tumor thrombus in the portal vein is described. Pancreatoduodenectomy with tube pancreatostomy was performed. The location and size of tumor thrombi in the portal vein could be determined accurately by intraoperative ultrasonography and removed with the wall of the portal vein and superior mesenteric vein. There was no evidence of recurrence one year after the operation. Tumor thrombus in the portal vein in gastric cancer is rarely reported and has a poor prognosis. If there is no associated liver metastasis, aggressive surgical approach followed by appropriate chemotherapy may prolong the life of the patient.