Thyroglossal duct cysts are common congenital abnormalities or developmental field defects, usually detected in early childhood. Despite their frequent occurrence, familial patterns are rare. We report on two new families with thyroglossal duct cysts. In the first family three siblings were involved, while in the second one, father and son were affected. This trait may be autosomal recessive or possibly multifactorial, as the first family would indicate, and also autosomal dominant, as the second family would suggest.