Thyroglossal duct remnants are the most common midline neck swellings, but carcinoma is found in approximately 1% of these lesions. The cysts are usually asymptomatic and the presentation of the patient with carcinoma is indistinguishable from the common cyst. Papillary adenocarcinoma comprises 75-85% of the tumors reported. A 36-year-old woman underwent Sistrunk procedure for excision of a thyroglossal cyst. No thyroid abnormality was noted pre-operatively nor during the surgical examination. The histopathological examination revealed papillary carcinoma. She has been maintained on thyroxine suppression and was doing well at 14 months' follow-up. Carcinoma of the thyroglossal duct cyst is rare. The ultrasonographic examination should be performed pre-operatively for thyroid gland study. The main question is what to do with the thyroid gland. There still is controversy about thyroid removal for a papillary carcinoma, but all the patients should receive suppressive doses of thyroid hormone. As the cure rate is 95% for the patients whose thyroid is preserved and further postoperative complications are avoided, we can consider that the optimal surgical procedure for thyroglossal duct carcinoma is the same as that for the benign cyst.