The authers have performed a clinical study on the thyroglossal duct cysts which were diagnosed and treated surgically in the department of Otolaryngology, National Medical Center during the period of last 12 years from 1962 to 1974. The following results were obtained : 1) Age distribution showed predilection for age 11~20 (37.5%), the youngest age of 2 and the oldest age of 56. 2) Sex incidence revealed 13 in male and 11 in female. 3) Duration revealed less then one year in 9 cases (37.5%) and between 1~5 years in 8 cases (33.3%). 4) 16 operated cases were thyroglossal cyst orduct. 5) Among the all cases, 5 cases have performed incision and drainage by other surgeon before they consult to us with poor improvement.