The majority of thyroid cancers are unilateral, and most of them are papillary, follicular and medullary carcinomas. For unilateral thyroid cancer, total thyroidectomy with isthmus resection on the affected side and subtotal thyroidectomy with lymph node dissection in the neck on the opposite side are performed. This can lead to a radical cure. In rare cases where thyroid cancer occurs bilaterally, total thyroidectomy may be considered. Therefore, the majority of thyroid cancers occur unilaterally. However, total excision of the affected side plus subtotal excision of the contralateral side together with isthmus is required.