A thyroid cyst is a type of thyroid nodule that is a nodular goiter, degenerative adenoma and old bleeding leading to cyst formation. Some thyroid cancers, especially papillary cancers, can also develop cystic changes. Therefore, once a thyroid cyst is detected, it is important to pay attention to: i. Clinical evaluation. The presence of local symptoms such as neck pain, hoarseness, dyspnea, and the presence of hyperthyroidism and hypothyroidism symptoms. Second, laboratory assessment. Thyroid function test, thyroid autoantibody test, thyroglobulin level measurement, serum calcitonin level measurement. Auxiliary tests: 1. thyroid ultrasound, 2. thyroid nuclear imaging, 3. MRI and CT, 4. PET to reflect the metabolic status of the lesion. Cytological evaluation. Fine needle aspiration biopsy tissue examination is currently considered to be the most valuable method to identify benign and malignant thyroid cysts. In conclusion, since there are two major categories of thyroid cysts, benign and malignant, clinical attention should be paid to the evaluation.