Differentiated thyroid carcinomas are rarely associated with macroscopic vascular invasion and intraluminal tumor thrombus in great cervical veins. The best treatment for such cases appears to be a total thyroidectomy with en-block resection of the involved vessels, followed by postoperative radioiodine therapy(RI). We report two cases of follicular thyroid carcinoma with vascular invasion and intraluminal tumor thrombosis in great cervical veins that were successfully treated using complete surgical resection and postoperative RI.