Thyroglossal duct cyst is ectodermal remnant, which may develop along the line of descent of the thyroid gland from the foramen cecum of the tongue to the pyramidal lobe of the thyroid gland. Meticulous dissection of the cyst and duct, along with the body of the hyoid bone is necessary to avoid recurrence. Eighty-one patients with thyroglossal duct cyst treated at Hanyang University Hospital between January 1980 and December 2000 were reviewed to determine the incidence and to analyze the result of management. The male-to-female ratio was 1.4:1(47:34) with a male preponderance. They are most commonly present at 3-8years(54.2 %) of age, but rarely present at infancy. The most common symptom was a painless midline neck mass(76.5 %, 62cases). Eighty-one patients underwent modified Sistrunk operation without evidence of recurrence. Eight-nine percent(72 cases) of these lesions were located between thyroid substance and hyoid bone, and 11 %(9 cases) were above the hyoid bone. There were 22 infected cysts(27.2 %). The Sistrunk operation is a gold standard for treating the thyroglossal duct cysts. For best results in thyroglossal duct cyst surgery, one should make every effort to remove the cyst intact in continuity with the body of the hyoid bone. In our institute, Sistrunk operation modified by the authors showed a good result.