The incidence and pathological features of papillary thyroid carcinoma arising in the thyroglossal duct cysts were reviewed and compared with papillary thyroid carcinoma arising elsewhere in the thyroid gland. In the 30 year period 1964 to 1993 there were 90 thyroglossal duct nodules or cysts treated surgically at the Endocrine Surgical Unit, Royal North Shore Hospital, Sydney, Australia. There were four cases of papillary thyroid carcinoma in this group (4.4%). In the same period 2814 cases presented with clinical single thyroid nodules which were treated surgically. There were 182 cancers in this group of which 121 were papillary thyroid carcinomas (4.3% of total cases). This is identical to the incidence seen in the thyroglossal duct. We conclude that the incidence of papillary thyroid carcinoma arising in the thyroglossal duct is no different to that arising elsewhere in the gland. The difference in number of carcinomas related only to the volume of follicular thyroid tissue present in the gland proper. That being the case, there is no reason to treat these cancers differently from papillary thyroid carcinoma elsewhere in the gland.