For the purpose of studying the appropriate surgical treatment for thyroid cancer in the early stage, extended modified neck dissection was carried out to examine node metastasis bilaterally in 22 patients considered preoperatively to be in this stage. These patients presented with only one movable unilateral nodule in the thyroid with no clinical evidence of nodal involvement. At the time of operation, as many vital structures as possible were preserved intact, resulting in a favorable postoperative course with no remarkable sequelae except for Horner's syndrome in one case. Since it was impossible to preserve the blood supply to the parathyroid glands as a consequence of adequate dissection of the tracheoesophageal nodes, they were totally removed and autotransplantated into the major pectoral muscle. As many as 20 patients (90.9%) had node metastases somewhere in the neck, of which [2 (54.5%) were bilateral. Some 224 (13.0%) out of the 1719 nodes dissected proved to contain metastases. Ineach case nodal involvement was found to be scattered over the entire neck region except for the contralateral submandibular nodes. The incidence of metastases in the inferior jugular nodes, para- and pretracheal group of the upper mediastinal nodes was 68.2%, 50.0% and 45.5%, respectively, implying the necessity Of mediastinotomy where possible for better results. Node metastases were also found in 31.8% of patients ipsilaterally as well as in 13.6% of patients contralaterally in the tracheoesophageal groove, where is the most critical point in the operation. The metastatic incidence of nodes overlying the thyroid cartilage and ipsilateral superior jugular nodes was as high as 36.4% and 50.0%, respectively. These results suggest that the thyroid cancer has already widely metastasized over the entire neck region at the time when the patient is diagnosed as having thyroid cancer, even if it is considered clinically to be in the early stage. Based upon these results, bilateral modified neck dissection, with mediastinotomy where possible, is considered the surgical treatment of choice for thyroid cancer. This operative method can be undertaken, according to our limited experience, without any remarkable complications or deleterious sequelae. *~ a·%~~~·~~~~·~*~~