The submucosal venous network of the esophagus is part of the collateral system that develops following superior vena caval obstruction from any cause. The direction of flow in these thin-walled, valveless veins is "downhill," towards the azygous vein or to the inferior vena cava. Bleeding from upper esophageal varices is extremely rare. This case report describes a patient with massive bleeding from upper esophageal varices secondary to superior vena caval obstruction by a malignant thyroid tumor. Total thyroidectomy relieved the obstruction, with cessation of hemorrhage and subsequent disappearance of the varices.