This review focuses on the pathologic criteria for completion thyroidectomy in well differentiated thyroid cancer as well the diagnosis and treatment of recurrent disease. The roles of ultrasound in the diagnosis of a cervical recurrence, its value in determining the extent of lymph node dissection in the lateral compartment, and the importance of intra-operative ultrasound in re-operative thyroid surgery are discussed. J. Surg. Oncol. 2006;94:714–718. © 2006 Wiley-Liss, Inc.