Bronchogenic cysts are rare congenital malformations that result from an abnormal development of the ventral foregut budding of the tracheobronchial tree at the time of organogenesis. They are usually located in the mediastinum and intrapulmonary regions. Localization in the cervical area is unusual, and specially, bronchogenic cysts presenting as thyroid and perithyroid cyst are quite rare. We report a case of bronchogenic cyst mimicking a thyroid colloid cyst. We tried percutaneous ethanol injection at 3 times for treatment of this thyroid cyst, but we failed, because of intractable cough. After cyst excision with thyroid lobectomy, we diagnosed the lesion to bronchogenic cyst. Bronchogenic cyst should be considered in the differential diagnosis of perithyroidal cyst, which especially the lesion is intolerable cyst to enthanol injection.