Thyroid surgery is a common procedure, and in recent years, the number of patients suffering from thyroid disease has increased, as has the number of patients with thyroid cancer compared to previous years. Before surgery, patients and their families often encounter doctors who inform them of the extent of thyroid removal during the conversation. Many patients often ask their doctors to preserve as much of the thyroid tissue as possible due to fear of surgery or fear of disability after organ removal. So, is the more thyroid tissue that is preserved the better? What about preserving a portion of the thyroid tissue even after the patient is diagnosed with thyroid cancer? From a professional point of view, especially for thyroid cancer, the answer is no. In the case of benign disease, such as thyroid adenoma, in the concern of side damage (such as damage to the recurrent laryngeal nerve) from surgery, the traditional domestic approach is to remove most of the thyroid tissue including the adenoma, which we call major or subtotal resection. In recent years, however, it is believed that patients with thyroid adenoma are prone to recurrence after surgery and that a single isolated adenoma is prone to carcinoma. Therefore, lobectomy of the affected thyroid gland is recommended for patients with thyroid adenoma, and with improved surgical skills, exploration of the recurrent laryngeal nerve is not as frightening, and the probability of side injuries after surgery is not increased. More importantly, after preserving a portion of the thyroid tissue, the incidence of postoperative complications (especially injury to the recurrent laryngeal nerve) is substantially higher if reoperation is required, compared to the risks associated with the initial total lobectomy. In the case of malignant disease, at least lobectomy + lymph node dissection of the affected side is required. If the tumor is large or follicular, or if the tumor invades the thyroid envelope or neck musculature, bilateral lobectomy + lymph node dissection or even neck dissection is required. What’s more, after thyroid surgery, thyroxine deficiency can be replaced with thyroxine tablets. Therefore, there is basically no need to worry about post-operative hypothyroidism. Therefore, thyroid surgery is not the best way to preserve as much thyroid tissue as possible.