Thyroid carcinoma has a unique biologic behavior characterized by early spread to regional lymph nodes and occasional extrathyroidal soft tissue extension but a low incidence of distant metastasis and infrequent disease-related death. Therefore, controversy exists over the proper extent of thyroidectomy and regional lymph node dissection in patients with differentiated thyroid carcinoma (DTC) and medullary thyroid carcinoma (MTC). The modest disease-specific mortality makes it unlikely that the extent of surgery will ever be the subject of a prospective randomized trial. Although more extensive cervical surgery may have only a limited effect on the duration of survival in patients with DTC, it may significantly improve quality of life by minimizing cervical recurrence. The high rates of cervical recurrence in patients with DTC and MTC have alerted physicians to the importance of fine-needle aspiration biopsy and ultrasonography for the diagnosis, preoperative staging, and follow-up of thyroid cancer. In patients with MTC, death caused by disease is uncommon in the absence of radiographically evident distant metastasis at the time of thyroidectomy. Cervical recurrence is even more common with MTC, and the need for compartment-oriented lymphadenectomy is accepted as standard surgical treatment to minimize disease recurrence. Postoperatively, calcitonin (CT) levels can be used to guide clinical management, but basal CT levels should not be used to direct the timing of prophylactic thyroidectomy in affected high-risk patients with familial MTC.