We performed a right transthoracic subtotal esophagectomy with systemic three-field lymph node dissection, followed by reconstruction with a gastric tube shifted retrosternally into the left side of the neck, for esophageal cancer in a 62-year-old woman. The patient had an uneventful postoperative course until postoperative day (POD) 9, when a venous thrombosis originating from the left brachiocephalic vein and elongating to the left subclavian vein was detected occasionally on computed tomography scans, although there were no clinical symptoms. The left brachiocephalic vein seemed narrowed by compression from the reconstructed gastric tube, and this was considered the cause of the thrombosis. The patient was commenced on thrombolytic therapy, using urokinase, and on anticoagulation therapy, using heparin and warfarin. The thrombus had disappeared completely by POD 38. The anticoagulation therapy was continued for 6 months and no recurrence of the thrombosis has been detected in the 4 months since its completion.