Recurrences after surgery for thyroglossal cysts and fistulas were common until, in 1920, Sistrunk described his technique for removing the whole thyroglossal tract. Since that time there has been considerable argument concerning the exact path taken by the tract particularly in relation to the hyoid bone. In an attempt to elucidate this problem, studies have been made of embryos at varying stages of development, of serially step-sectioned adult larynges and of surgical specimens. These studies suggest that the thyroglossal tract occupies a constant and embryologically predictable position in relation to the hyoid bone and they support the rationale of Sistrunk's procedure.