Among benign cervical masses, thyroglossal duct cyst in one of the most frequently encountered. It is congenital in origin, and its sinus in the neck results from spontaneous rupture of cyst due to inflammation, surgical drainage of the cyst, or inadequate excision. We have performed a clinical study on 30 cases of thyroglossal duct cysts and sinuses which were diagnosed and treated surgically in the Dept. of Otolaryngology, Maryknoll General Hospital, Pusan from February, 1979 to July, 1987. Results are as follows ; 1) Age distribution showed predilection under 20yr. age(63.3%) and sex incidence revealed 17 in male and 13 in female. 2) Average duration of symptom prior to hospital entry was 7 years and 1 month. 3) The types were cysts 21 cases and sinuses 9 cases. 4) The lesions were found on the midline of the neck in 27 cases and left lateral of the neck in 3 cases. 5) The thyroglossal tracts passed above the hyoid in 27 cases and below the hyoid in 3 cases. 6) There was no connection with thyroid gland in entire cases. 7) In microscopic examination, 4 cases revealed thyroid tissue within the wall of cyst or sinus tract and lining epitheliums were squamous in 25 cases and columnar in 14 cases. 8) The entire cases were operated according to the Sistrunk procedure. 9) There was 1 recurrence, but other complication was not seen.