Thyroglossal duct cysts result from failure to obliterate the embryonic throglossal duct. When these cysts drain through the skin, they produce thyroglossal duct fistulas, which re often infected. We report two cases of thyroglossal duct fistula in an 8-year-old boaid a 41-year-old man who had a infected cystic mass and sirius on the anterior midline neck, respeticely. The cyst which is lined by a columnar epithelium was identified microscopically in a surgically n se ted specimen. (Kor J Dermatol 1995;33(3): 510-519)