Cancers of the thyroglossal tract are very rare. Seventy-four patients with a cyst of the thyroglossal tract were operated in our hospital between 1978 and 1991. A papillary carcinoma was discovered on histological examination in one case. This cancer was treated by Sistrunk's operation. The patient had no sign of recurrence one five years after the operation. This paper presents the case report of this unusual cancer of which fewer than 100 similar cases have been reported in the literature.