Uit de Keel-Neus-Ooorheelkundige Universiteitscliniek te Amsterdam, Directeur prof. Dr. A. De Kleyn. Killian (1908) demonstrated the existence of a physiological borderline between hypopharynx and eosophagus: the oesophagus-mouth. The so-called pulsion theory of Zenker is now on a physiological basis. The pulsion diverticulum of Zenker is a hypopharynx diverticulum. The symptoms are discussed; X-ray examination and oesophagoscopy are of definite value for diagnosis (ulcers in the wall of the diverticulum). The various operative procedures are descriptionbed; the removal of the sac in one or two stages is most commonly used.